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Working with replication links


A replication link provides all the information the replication service needs to perform its functions. You can create a link in the HCP System Management Console for either of the systems involved in the link.

When you create a link, you specify whether it is active/active, the outbound side of an active/passive link (that is, the primary system), or the inbound side of an active/passive link (that is, the replica). Once a link exists, you can select HCP tenants, default-namespace directories, and, for active/passive links only, other links to replicate on the link.

You can modify replication links at any time. You can also delete replication links. However, this action should be taken only with a full understanding of the consequences.

This section of the Help contains considerations and instructions for performing the activities mentioned above. For information on changing the time periods and intensity at which activity occurs on a link, see Scheduling activity on a replication link.

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Roles: To view a replication link, you need the monitor or administrator role. To create, manage, modify, or delete a replication link, you need the administrator role.

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Note: You can also use the HCP management API to create, manage, modify, and delete replication links. For information on doing this, see Replication resources.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Link properties


You create a replication link on either one of the systems you want to participate in the link. When you first create the link, you set these properties:

The link name.

Optionally, a description of the link.

The link type. This can be active/active, outbound (for an active/passive link you’re creating on the primary system), or inbound (for an active/passive link you’re creating on the replica).

Whether HCP should compress and/or encrypt data before transmitting it to the other system. For an active/active link, these settings apply to data being replicated in both directions on the link.

Whether priority should be given to objects with the oldest changes, regardless of namespace, or processing should be balanced across namespaces. For an active/active link, this setting applies to both systems involved in the link.

The identity of the other system you want to participate in the link. You can identify the other system either by domain name or by the IP addresses of storage nodes in that system.

The port on which the other system will listen for transmissions from the system where you’re creating the link. Typically, you accept the default of 5748.

If the system where you’re creating the link uses network address translation (NAT):

oThe domain name or IP addresses the other system should use to communicate with the system where you’re creating the link

oThe port on which the system where you’re creating the link will listen for transmissions from the other system

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Note: If either or both of the systems involved in a link use a NAT, the NAT or NATs must be configured for port forwarding.

When you create a link, the automatic failover and failback properties default to disabled. You cannot modify these properties during link creation. For instructions on modifying them for an existing link, see Changing automatic failover and failback settings.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Considerations for creating a replication link


These considerations apply to creating replication links:

You cannot create a replication link between a release 8.x HCP system and a system earlier than release 7.0.

You can create a replication link only after you have installed the required SSL certificates, as described in Configuring SSL for replication.

You can create multiple replication links between the same two systems. However, the links cannot include the same HCP tenants and default-namespace directories. Also, only one of the links can be used in an erasure coding topology.

If you don’t want HCP tenant-level users to see replication details, you should deselect the option that allows this before you create the replication link. For more information on this, see Controlling the Tenant Management Console replication display.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Creating a replication link


To create a replication link:

1.In the top-level menu of the HCP System Management Console, select Services Replication.

2.On the replication Links page, click on Create Link.

The link creation wizard opens.

3.On the wizard Name page:

oIn the Name field, type a name for the link. Link names must be from one through 64 characters long and can contain any valid UTF‑8 characters, including white space. Link names are not case sensitive.

Link names must be unique within a replication topology.

oOptionally, in the Description field, type a description for the link. The description can be up to 1,024 characters long and can contain any valid UTF-8 characters, including white space.

4.Click on Next.

5.On the wizard Settings page:

oIn the Link Type section:

To create an active/active link, select Active/Active.

To create an active/passive link for which the system where you’re creating the link is the primary system, select Outbound.

To create an active/passive link for which the system where you’re creating the link is the replica, select Inbound.

oIn the Data Transfer section:

Optionally, to compress data before it’s transmitted from one system to the other, select Compress data.

Compressing data increases network throughput but also increases processing time. Therefore, because compression applies to all transmitted data, you should enable compression only if most of the data being replicated is compressible.

To enable or disable the encryption of data before it’s transmitted from one system to the other, select or deselect Encrypt data.

By default, data encryption is enabled on replication links. Encryption keeps the data confidential during transmission. The transmitted data is automatically decrypted on the target system. If you have disabled encryption on replication links and want to enable it again, select Encrypt data.

If you have disabled encryption on replication links, data is transmitted unencrypted, even if the data is encrypted on the system sending the data. Regardless of whether the data is encrypted before transmission, the data is still secured by SSL during transmission.

If the HCP system does not support HTTPS for data transmission, the Encrypt data option is not present.

oIn the Replication Priority section:

To have the replication service balance its processing time evenly across the namespaces being replicated, select Balanced across namespaces.

To replicate objects with the oldest changes first, regardless of which namespaces they’re in, select Oldest object first.

6.Click on Next.

7.On the wizard Connection page:

oIn the Remote Hostname or IP Addresses field, type either the domain name of the other system you want to participate in the link or one or more comma-separated IP addresses of storage nodes in that system. For the domain name, use either of these formats:

replication.hcp-domain-name

replication.admin.hcp-domain-name

In these formats, hcp-domain-name must be the name of the domain associated with the network that’s selected for replication on the other system. For example, if the domain name is hcp-ca.example.com, you specify this in the Remote Hostname or IP Addresses field when using the second format shown above:

replication.admin.hcp-ca.example.com

For information on when the second format is required, see Displaying the zone definition for the replication network domain.

If you specify IP addresses for one or more nodes, they must be IP addresses in the network that’s selected for replication on the other system.

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Note: If you specify a domain name, the system where you’re creating the link transmits data to all storage nodes in the other system. If you specify IP addresses, the system where you’re creating the link transmits data to only those nodes. Therefore, you should specify IP addresses only if you have a compelling reason to do so (for example, HCP is not using DNS, or you need to reduce the processing load on some number of nodes).

oOptionally, to specify a different port for the other system to listen on or to specify network address translation (NAT) information for the system where you’re creating the link, click on Advanced Configuration. Then, in the Advanced Configuration section, as applicable:

In the Remote Port field, type the number of the port on which the other system will listen for data from the system where you’re creating the link. The default port is 5748. Typically, you specify a different port only if other port usage makes using a different port necessary.

If the system where you’re creating the link uses NAT for communication with the other system, specify the target for data transmissions from the other system:

In the Local Hostname or IP Addresses field, type either the name of the domain associated with the network that’s selected for replication on the system where you’re creating the link (as that name is known to the other system) or one or more comma-separated IP addresses of storage nodes in that network (as those addresses are known to the other system). For the domain name, use either of these formats:

replication.hcp-domain-name

replication.admin.hcp-domain-name

For information on when the second format is required, see Displaying the zone definition for the replication network domain.

Make sure the other system can resolve the domain name you specify.

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Note: The other system will transmit data only to the nodes identified by the domain name or IP addresses you specify. Therefore, if you’re using IP addresses, you should specify the addresses of all the storage nodes in the system.

In the Local Port field, type the number of the port on which the system where you’re creating the link will listen for data from the other system. This is the port that’s exposed to the other system.

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Note: For network configurations that use NAT, multiple IP addresses must be configured to expose the HCP nodes. You cannot use multiple ports on the same IP address.

8.Click on Next.

9.On the wizard Review page, review the link configuration.

10.If the link configuration is what you want, click on Finish to create the link.

If the link configuration is not what you want, use the Previous button in the wizard to return to pages on which you want to make corrections. Alternatively, press Cancel to leave the wizard without creating the link.

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Tip: If HCP cannot create the configured link, check that the other system is healthy and that you’ve correctly shared SSL server certificates between the two systems.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Considerations for specifying link content


These considerations apply to specifying the content for replication links:

The content for a replication link (that is, what is replicated on the link) consists of any number of:

oHCP tenants

oHCP namespaces

oDirectories defined in the default namespace

oFor active/passive links only, chained links

You can add a tenant to a replication link only if the tenant is configured to allow replication.

You cannot add a tenant to a replication link between two systems if another link between the same two systems already includes that tenant.

You can choose which namespaces to replicate for any given HCP tenant only if the tenant has granted system-level users administrative access to itself. Namespaces that are selected for replication are replicated on every link that includes the owning tenant.

To select and deselect HCP namespaces for replication, you can use any link that includes the owning tenant.

You can add and remove HCP tenants, default-namespace directories, and chained links from a replication link at any time, except during an upgrade of either system involved in the link, while the link is failed over, while data recovery is occurring on the link, or while the two systems involved in the link cannot communicate with each other.

When you add an HCP tenant to an erasure coding topology, the tenant is automatically added to every link in that topology. For more information on adding tenants to erasure coding topologies, see Considerations for specifying the tenants for an erasure coding topology.

When you add an HCP tenant to a replication link without adding the tenant to an erasure coding topology, all replication-enabled namespaces owned by the tenant use whole-object protection regardless of whether they are configured to allow erasure coding.

You cannot add an HCP tenant to a replication link while that tenant is included in an active, retiring , or retired erasure coding topology that includes one or both of the systems involved in the link but not the link itself.

You cannot remove an HCP tenant from a replication link that's part of an active erasure coding topology.

You cannot remove an HCP tenant from a replication link if that tenant was previously removed from the active erasure coding topology and any of the tenant's namespaces still contain chunks for erasure-coded objects.

You cannot remove an HCP tenant from a replication link that's part of a retiring erasure coding topology if any of the tenant's namespaces still contain chunks for erasure-coded objects.

You can select HCP namespaces for replication at any time, except during an upgrade of either system involved in the link you started from. You can deselect HCP namespaces from replication at any time, except during an upgrade of either system involved in the link you started from, while a link that includes the owning tenant is failed over, or while data recovery is occurring on a link that includes the owning tenant.

After removing an HCP tenant or default-namespace directory from an active/active replication link, you can add the tenant or directory back to that link. While the tenant or directory is not on the link, operations on that tenant or directory, on replicated namespaces owned by that tenant, or on objects in those replicated namespaces or in that directory can occur on both systems involved in the link.

Similarly, after deselecting a namespace for replication, you can select it again. If the tenant that owns the namespace is on an active/active link, while the namespace is deselected, operations on objects in the namespace can occur on both systems involved in the link.

These considerations apply:

oWhen you add a replicated tenant back to a link:

If you deleted the tenant on either system involved in the link while the tenant was not on the link, the tenant is replicated back to that system

If you deleted any of the tenant's replicated namespaces on either system involved in the link while the tenant was not on the link but you did not delete the tenant, those namespaces are replicated back to that system

If you deleted any objects in any of the tenant's replicated namespaces on either system involved in the link while the tenant was not on the link but you did not delete the tenant or those namespaces, those objects are deleted on the other system

oWhen you add a replicated directory back to a link:

If you deleted the directory on either system involved in the link while the directory was not on the link, the delete operation is replicated to the other system

If you deleted any objects in the directory on either system involved in the link while the directory was not on the link but you did not delete the directory, those objects are deleted on the other system.

oWhen you add a replicated tenant or directory back to a link or reselect a replicated namespace for replication, all operations that occurred in that tenant, directory, or namespace on either system while replication was not happening are replicated to the other system (except for the deletion of the tenant or namespace). During this replication, conflicts can occur between changes made on different systems while the tenant, directory, or namespace was not being replicated. For information on how HCP resolves these conflicts, see Replication collisions.

After removing an HCP tenant or default-namespace directory from an active/passive link, you cannot add the tenant or directory back to that link unless you first delete the tenant or directory from the replica. This is because the tenant or directory now already exists on the replica.

When you add one or more default-namespace directories to a link, some objects in directories that were already on the link may be reprocessed. This can increase the replication backlog for the default namespace.

You cannot add an HCP tenant to an active/passive link if the same tenant already exists on the replica. Two tenants are the same as each other if they have the same internal ID.

The only way the same tenant can exist on two systems is if it was created on one system and then replicated to the other system. Changing the name of the tenant on either of the systems does not make the two tenants different from each other.

You cannot add an HCP tenant to any type of replication link if a different tenant with the same name already exists on the other system involved in the link. In this case, however, if you change the name of the tenant on either of the systems involved, you can add the tenant to the link.

You cannot add a default-namespace directory to an active/passive link if a directory with the same name already exists on the replica. If the directory is empty on the primary system or the replica, you can change the directory name on that system. Then you can add the directory to the link.

You cannot chain a replication link between system A and system B into an active/passive link between system B and system C if an HCP tenant on the first link has the same name as a different tenant that already exists on system C. However, if you change the name of the tenant on system A or system C, you chain the first link into the second link.

You cannot chain a replication link between system A and system B into an active/passive link between system B and system C if an HCP tenant on the first link is the same as a tenant that already exists on system C, regardless of whether the tenant names are the same.

You cannot chain a replication link between system A and system B into an active/passive link between system B and system C if a default-namespace directory on the first link has the same name as a default-namespace directory that already exists on system C.

In a replication chain with the configuration ABC, if you add an HCP tenant to the link from system A to system B and the same tenant already exists on system C, replication of that tenant from system B to system C is automatically paused. To recover from this situation:

1.Either delete the tenant on system C, or remove the tenant from the link from system A to system B.

2.Resume replication of the tenant on the link from system B to system C.

For information on resuming replication of a tenant, see Pausing and resuming replication or recovery of a tenant.

In a replication chain with the configuration ABC, if you add an HCP tenant to the link from system A to system B and a different tenant with the same name already exists on system C, replication of that tenant from system B to system C is automatically paused. To recover from this situation:

1.Either rename the tenant on system C, delete the tenant on system C, or remove the tenant from the link from system A to system B.

2.Resume replication of the tenant on the link from system B to system C.

In a replication chain with the configuration ABC, if you add a default-namespace directory to the link from system A to system B and a default-namespace directory with the same name already exists on system C, replication of the default tenant from system B to system C is automatically paused. To recover from this situation:

1.Either rename the directory on system C, delete the directory on system C, or remove the directory from the link from system A to system B. The first two options are possible only if the directory is empty on system C.

2.Resume replication of the default tenant on the link from system B to system C.

In a replication chain with the configuration ABC, if you add a default-namespace directory to the link from system A to system B and either of these is true, replication of the default tenant from system B to system C is automatically paused:

oThe default namespace doesn’t exist on system C. To recover from this situation:

1.Create the default namespace on system C with the same retention mode and cryptographic hash algorithm as the default namespaces on systems A and B have.

2.Resume replication of the default tenant on the link from system B to system C.

oThe default namespace exists on system C but has a different retention mode or cryptographic hash algorithm from the default namespaces on systems A and B. To recover from this situation:

1.Delete the default-namespace directory from the link from system A to system B.

2.Resume replication of the default tenant on the link from system B to system C.

On the Replication page in the System Management Console, each panel in which you can add and remove items of a specific type to and from a replication link includes a list of the items of the applicable type that are already included on the link. In those lists, rows containing items that have been deleted from HCP are highlighted in red and have a trash can icon ( DeletedRedTrashCan.png ) on the right.

HCP automatically removes each deleted namespace from a link after the deletion has been replicated. You need to remove deleted tenants and directories yourself.

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Important: Do not remove a deleted item from a replication link until after the deletion has been replicated.

If you deselect a namespace from replication, any further action on that namespace, including deletion of the namespace, is not replicated. This enables a situation in which the owning tenant can end up with more namespaces than are allowed by its namespace quota and/or using more storage than is allowed by its hard quota.

For example, consider the following scenario for a tenant has reached its namespace quota of five:

1.The tenant is selected for replication on an active/passive link, along with all five of its namespaces.

The tenant now has five namespaces on both the primary system and the replica.

2.One of the namespaces is removed from the replication link.

3.On the primary system, the tenant empties and deletes the removed namespace.

The tenant now has four namespaces on the primary system and five namespaces on the replica.

4.On the primary system, the tenant creates a new namespace.

The tenant now has five namespaces on the primary system and five namespaces on the replica, but the namespaces on the two systems are not the same ones.

5.The new namespace is added to the replication link.

The tenant now has five namespaces on the primary system and six namespaces on the replica.

A namespace can contain metadata-only objects on one or more HCP systems in a replication topology. If such a system is involved in only one replication link that includes the tenant that owns the namespace, the following actions can result in the data for those metadata-only objects becoming inaccessible from that system, possibly permanently:

oYou remove the tenant that owns the namespace from the link. In this case, to make the data accessible again:

If the link is active/active, add the tenant back into the link.

If the link is active/passive, either change the link to active/active, or create a new active/active link between the same two systems. Then add the tenant back to the changed link or to the new link, as applicable.

oYou deselect the namespace from replication. In this case, to make the data accessible again, reselect the namespace.

oThe tenant that owns the namespace is included on the first link in a replication chain, the namespace with the metadata-only objects is on the third HCP system in the chain, and you remove the first link from the link to the third system. In this case, to make the data accessible again:

1.If the first link in the chain is active/passive, change the link to active/active.

2.Either change the link to the third system to active/active, or create a new active/active link between the second and third systems in the chain.

3.Add the tenant back to the changed link to the third system or to the new link, as applicable.

oThe namespace with the metadata-only objects is on the third HCP system in a replication chain, and you remove the tenant that owns the namespace from the first replication link in the chain. In this case, to make the data accessible again:

1.Create a new active/active link between the first and second systems in the replication chain.

2.Add the tenant to the new link.

HCP displays a warning about metadata-only objects when you submit a request to delete an active/passive link or to remove a tenant from an active/passive link while any of the namespaces being replicated on the link contain metadata-only objects.

For more information on metadata-only objects, see Administering HCP.

You can add an HCP tenant to a replication link on one of the systems involved in the link even if the management and data access networks associated with that tenant aren’t defined on the other system involved in the link. However, if these networks are not defined on the other system, the tenant and its namespaces will be inaccessible on that system.

If a network associated with a tenant is undefined in a given system, the tenant list on the Tenants page in the System Management Console for that system shows this alert for the tenant: TenantNetworkInaccessible.png

For more information on networks, see Network administration.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Specifying link content


To specify the content for a replication link:

1.In the top-level menu of the HCP System Management Console for either system involved in the link, select Services Replication.

2.On the replication Links page, click on the link for which you want to specify content.

3.On the replication link details page, click on Content.

4.In the Content panel, take either of these actions:

oTo specify content for an active/active link, follow the instructions in Specifying link content for an active/active link.

oTo specify content for an active/passive link, follow the instructions in Specifying link content for an active/passive link.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Specifying link content for an active/active link


To specify content for an active/active link, take one or more of these actions in the Content panel for the link:

To add and remove HCP tenants to and from the link, click on the Tenants tab. Then follow the instructions in Adding and removing HCP tenants in an active/active link.

To select and deselect namespaces for replication, follow the instructions in Selecting and deselecting HCP namespaces for tenants in an active/active link.

Selected namespaces are replicated on every link that includes the owning tenant.

To add and remove default-namespace directories to and from the link, click on the Default Tenant tab. Then follow the instructions in Adding and removing default-namespace directories in an active/active link.

The Default Tenant tab is present only if the default namespace exists on the local system.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Adding and removing HCP tenants in an active/active link


The link content Tenants panel for an active/active link has these sections:

Tenants Replicating — Lists the HCP tenants already included on the link.

Local Tenants — Lists the HCP tenants on the local system that are eligible for replication but not currently included on the link. This list does not include tenants that are read-only on the local system due to replication.

Remote Tenants — Lists the HCP tenants on the other system involved in the link that are eligible for replication but not currently included on the link. This list does not include tenants that are read-only on the other system due to replication.

If a tenant has granted system-level users administrative access to itself, the row for the tenant in the applicable list shows the number of the tenant's namespaces that are selected for replication. On the primary system for an active/passive link, the row shows this number out of the total number of namespaces owned by the tenant.

To add HCP tenants to an active/active link, in the link content Tenants panel:

1.Optionally, filter the list from which you want to select one or more tenants to add to the link. For instructions on doing this, see Filtering item selection lists.

2.In the applicable list, select the tenants you want to add to the link.

To select all the tenants in the list, click on Select All above the list.

To deselect all the selected tenants, click on Clear above the list.

3.Click on Add Selected Tenants below the applicable list.

To remove HCP tenants from an active/active link, in the link content Tenants panel:

1.Optionally, in the Tenants Replicating section, filter the list of tenants that are currently included on the link. For instructions on doing this, see Filtering item selection lists.

2.In the tenants replicating list, select the tenants you want to remove from the link.

To select all the tenants in the list, click on Select All above the list.

To deselect all the selected tenants, click on Clear above the list.

3.Click on Remove Selected Tenants.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Selecting and deselecting HCP namespaces for tenants in an active/active link


You select and deselect HCP namespaces for replication in the Manage Namespaces window for the tenant that owns the namespaces. To open this window, in the link content Tenants panel, click on the manage namespaces control ( NamespacesControl.png ) for the owning tenant. This control is present only if the tenant has granted system-level users administrative access to itself.

When you start from an active/active link, the Manage Namespaces window has these sections:

Namespaces Selected for Replication — Lists the tenant's namespaces that are currently selected for replication

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Important:  

In the Namespaces Selected for Replication section, rows containing namespaces that have been deleted from HCP are highlighted in red and have a trash can icon ( DeletedRedTrashCan.png ) on the right. HCP automatically removes each deleted namespace from this list after the deletion has been replicated.

Do not manually remove deleted namespaces from this list. If you do, the deletion will not be replicated.

Disabling replication for a namespace that has already been replicated may cause object data in that namespace to become inaccessible on one or more systems in the replication topology.

Local Namespaces — Lists the namespaces that are owned by the tenant on the local system and that are not currently selected for replication

Remote Namespaces — Lists the namespaces that are owned by the tenant on the other system involved in the link and that are not currently selected for replication

To close the Manage Namespaces window without taking any action, click on the close control ( CloseControl.png ) in the upper right corner.

To select HCP namespaces for replication when you start from an active/active link, in the Manage Namespaces window:

1.Optionally, filter the list from which you want to select one or more namespaces for replication. For instructions on doing this, see Filtering item selection lists.

2.For each listed namespace you want to select for replication, click in the namespace row.

The namespace is selected, and the namespace row changes color.

To select all the namespaces in the list, click on Select All above the list.

To deselect a selected namespace, click in the namespace row.

To deselect all the selected namespaces, click on Clear.

3.Click on Add Selected Namespaces below the list.

To deselect HCP namespaces from replication when you start from an active/active link, in the Manage Namespaces window:

1.Optionally, in the Namespaces Selected for Replication section, filter the list of namespaces that are currently selected for replication. For instructions on doing this, see Filtering item selection lists.

2.For each listed namespace you want to deselect from replication, click in the namespace row.

The namespace is selected, and the namespace row changes color.

To select all the namespaces in the list, click on Select All above the list.

To deselect a selected namespace, click in the namespace row.

To deselect all the selected namespaces, click on Clear.

3.Click on Remove Selected Namespaces below the list.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Adding and removing default-namespace directories in an active/active link


The link content Default Tenant panel for an active/active link has these sections:

Directories Replicating — Lists the HCP default-namespace directories already included on the link.

Local Directories — Lists the default-namespace directories on the local system that are not currently included on the link. This list does not include directories that are read-only on the local system due to replication.

Remote Directories — Lists the default-namespace directories on the other system involved in the link that are not currently included on the link. This list does not include directories that are read-only on the other system due to replication.

To add default-namespace directories to an active/active link, in the link content Default Tenant panel:

1.Optionally, filter the list from which you want to select one or more directories to add to the link. For instructions on doing this, see Filtering item selection lists.

2.In the applicable directory list, select the directories you want to add to the link.

To select all the directories in the list, click on Select All above the list.

To deselect all the selected directories, click on Clear above the list.

3.Click on Add Selected Directories below the applicable list.

To remove default-namespace directories from an active/active link, in the link content Default Tenant panel:

1.Optionally, in the Directories Replicating section, filter the list of directories that are currently on the link. For instructions on doing this, see Filtering item selection lists.

2.In the list of replicating directories, select the directories you want to remove from the link.

To select all the directories in the list, click on Select All above the list.

To deselect all the selected directories, click on Clear above the list.

3.Click on Remove Selected Directories below the list.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Specifying link content for an active/passive link


To specify content for an active/passive link, take one or more of these actions in the Content panel for the link:

To add and remove HCP tenants to and from the link, click on the Tenants tab. Then follow the instructions in Adding and removing HCP tenants in an active/passive link.

To select and deselect namespaces for replication, follow the instructions in Selecting and deselecting HCP namespaces for tenants in an active/passive link.

Selected namespaces are replicated on every link that includes the owning tenant.

To add and remove default-namespace directories to and from the link, click on the Default Tenant tab. Then follow the instructions in Adding and removing default-namespace directories in an active/passive link.

The Default Tenant tab is present only if the default namespace exists on the local system.

To add and remove chained links to and from the link, click on the Chained Links tab. Then follow the instructions in Adding and removing chained links in an active/passive link.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Adding and removing HCP tenants in an active/passive link


The link content Tenants panel for an active/passive link has these sections:

Tenants Replicating — Lists the HCP tenants already included on the link.

Local Tenants — For outbound links only, lists the HCP tenants on the local system that are eligible for replication but not currently included on the link. This list does not include tenants that are either:

oRead-only on the local system due to replication

oIncluded on a link that is chained into the current link

This section is not present for inbound links.

Remote Tenants — For inbound links only, lists the HCP tenants on the other system involved in the link that are eligible for replication but not currently included on the link. This list does not include tenants that are either:

oRead-only on the other system due to replication

oIncluded on a link that is chained into the current link

This section is not present for outbound links.

If a tenant has granted system-level users administrative access to itself, the row for the tenant shows the number of the tenant's namespaces that are selected for replication.

To add or remove HCP tenants in an active/passive link, in the link content Tenants panel:

1.Take either or both of these actions:

oTo add HCP tenants to the link:

1.Optionally, filter the list of tenants in the Local Tenants or Remote Tenants section, as applicable. For instructions on doing this, see Filtering item selection lists.

2.In the applicable list, select the tenants you want to add to the link.

To select all the tenants in the list, click on Select All above the list.

To deselect all the selected tenants, click on Clear above the list.

oTo remove HCP tenants from the link:

1.Optionally, filter the list of tenants in the Tenants Replicating section. For instructions on doing this, see Filtering item selection lists.

2.In the list of replicating tenants, select the tenants you want to remove from the link.

To select all the tenants in the list, click on Select All above the list.

To deselect all the selected tenants, click on Clear above the list.

2.Click on Update Link.

If you’re removing tenants from the link, a confirming message appears.

In the window with the confirming message, select I understand to confirm that you understand the consequences of your action. Then click on Update Link.

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Selecting and deselecting HCP namespaces for tenants in an active/passive link


You select and deselect HCP namespaces for replication in the Manage Namespaces window for the tenant that owns the namespaces. To open this window, in the link content Tenants panel, click on the manage namespaces control ( NamespacesControl.png ) for the owning tenant. This control is present only if the tenant has granted system-level users administrative access to itself.

When you start from an active/passive link, the Manage Namespaces window has these sections:

Namespaces Selected for Replication — Lists the tenant's namespaces that are currently selected for replication.

ImportantWebHelp.png

Important:  

In the Namespaces Selected for Replication section, rows containing namespaces that have been deleted from HCP are highlighted in red and have a trash can icon ( DeletedRedTrashCan.png ) on the right. HCP automatically removes each deleted namespace from this list after the deletion has been replicated.

Do not manually remove deleted namespaces from this list. If you do, the deletion will not be replicated.

Disabling replication for a namespace that has already been replicated may cause object data in that namespace to become inaccessible on one or more systems in the replication topology.

Select Namespaces for Replication — Lists the tenant's namespaces that are not currently selected for replication.

To close the Manage Namespaces window without taking any action, click on the close control ( CloseControl.png ) in the upper right corner.

To select or deselect HCP namespaces for replication when you start with an active/passive link, in the Manage Namespaces window:

1.Take either or both of these actions:

oTo select HCP namespaces for replication:

1.Optionally, filter the list of namespaces in the Select Namespaces for Replication section. For instructions on doing this, see Filtering item selection lists.

2.For each listed namespace you want to select for replication, click in the namespace row.

The namespace is selected, and the namespace row changes color.

To select all the namespaces in the list, click on Select All above the list.

To deselect a selected namespace, click in the namespace row.

To deselect all the selected namespaces, click on Clear.

oTo deselect HCP namespaces from replication:

1.Optionally, filter the list of namespaces in the Namespaces Selected for Replication section. For instructions on doing this, see Filtering item selection lists.

2.For each listed namespace you want to deselect from replication, click in the namespace row.

The namespace is selected, and the namespace row changes color.

To select all the namespaces in the list, click on Select All above the list.

To deselect a selected namespace, click in the namespace row.

To deselect all the selected namespaces, click on Clear.

2.Click on Update.

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Adding and removing default-namespace directories in an active/passive link


The link content Default Tenant panel for an active/passive link has these sections:

Directories Replicating — Lists the default-namespace directories already included on the link.

Local Directories — For outbound links only, lists the default-namespace directories on the local system that are not currently included on the link. This list does not include directories that are either:

oRead-only on the local system due to replication

oIncluded on a link that is chained into the current link

This section is not present for inbound links.

Remote Directories — For inbound links only, lists the default-namespace directories on the other system involved in the link that are not currently included on the link. This list does not include directories that are either:

oRead-only on the other system due to replication

oIncluded on a link that is chained into the current link

This section is not present for outbound links.

To add or remove default-namespace directories in an active/passive link, in the link content Default Tenant panel:

1.Take either or both of these actions:

oTo add default-namespace directories to the link:

1.Optionally, filter the list of directories in the Local Directories or Remote Directories section, as applicable. For instructions on doing this, see Filtering item selection lists.

2.In the applicable directory list, select the directories you want to add to the link.

To select all the directories in the list, click on Select All above the list.

To deselect all the selected directories, click on Clear above the list.

oTo remove default-namespace directories from the link:

1.Optionally, filter the list of directories in the Directories Replicating section. For instructions on doing this, see Filtering item selection lists.

2.In the list of replicating directories, select the directories you want to remove from the link.

To select all the directories in the list, click on Select All above the list.

To deselect all the selected directories, click on Clear above the list.

2.Click on Update Link.

If you’re removing directories from the link, a confirming message appears.

In the window with the confirming message, select I understand to confirm that you understand the consequences of your action. Then click on Update Link.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Adding and removing chained links in an active/passive link


The link content Chained Links panel for an active/passive link has these sections:

Links Replicating — Lists the links already included in the current link.

Local Links — For outbound links only, lists the active/active links in which the current link participates and the active/passive links for which the current system is the replica.

This section is not present for inbound links.

Remote Links — For inbound links only, lists the active/active links in which the other system involved in the current link participates and the active/passive links for which the other system involved in the current link is the replica.

This section is not present for outbound links.

To view the content of a link in any of the lists described above:

1.Click on the view content control ( InboundLinkContent.png ) for the link.

2.In the Link Content window:

oTo see a list of the HCP tenants included on the link, click on the Tenants tab.

oTo see a list of the default-namespace directories included on the link, click on the Default Tenant tab.

oTo see a list of the chained links included in the link, click on the Chained Links tab.

You can filter any of these lists to display a subset of the listed items. For instructions on doing this, see Filtering item selection lists.

3.When you’ve finished viewing the link content, click on Close.

To add or remove chained links in an active/passive link, in the link content Chained Links panel:

1.Take either or both of these actions:

oTo add chained links to the current link:

1.Optionally, filter the list of links in the Local Links or Remote Links section, as applicable. For instructions on doing this, see Filtering item selection lists.

2.In the applicable list, select the links you want to add to the current link.

To select all the links in the list, click on Select All above the list.

To deselect all the selected links, click on Clear above the list.

oTo remove chained links from the current link:

1.Optionally, filter the list of links in the Links Replicating section. For instructions on doing this, see Filtering item selection lists.

2.In the list of replicating links, select the links you want to remove from the current link.

To select all the links in the list, click on Select All above the list.

To deselect all the selected links, click on Clear above the list.

2.Click on Update Link.

If you’re removing chained links from the current link, a confirming message appears.

In the window with the confirming message, select I understand to confirm that you understand the consequences of your action. Then click on Update Link.

For a discussion of chained replication, see Active/passive chained replication.

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Filtering item selection lists


By default, the lists you use to add and remove items in replication links contain all of the applicable items. You can filter any of these lists to display a subset of the applicable items. A filtered list contains only those items with a name that begins with or is the same as a specified text string.

You cannot filter a list while any of the items in it are selected.

To filter a list:

1.In the field above the list, type the text string you want to use as a filter. This string can be up to 64 characters long, can contain any valid UTF-8 characters, and is not case sensitive. White space is allowed.

2.Click on the find control ( FindControl.png ).

To redisplay the entire list, click on the clear filter control ( ClearFilterControl.png ).

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Considerations for modifying a replication link


These considerations apply to modifying replication links:

You can modify a replication link in the HCP System Management Console for either system involved in the link.

You can modify a replication link at any time.

You can change an active/passive link to an active/active link, but you cannot change an active/active link to an active/passive link.

When changing an active/passive link to active/active, you need to ensure that replication checkpoints are up to date before converting, otherwise you risk losing directory metadata.

You cannot change the direction of an active/passive link.

If you change the domain name or IP addresses for either system involved in a link, the new domain name or IP addresses must identify the same system. The exception to this is when you’re reconfiguring the link before restoring it to a new or rebuilt system.

When you change an active/passive link to an active/active link, HCP suspends activity on the link. You need to resume activity on the link manually. For information on resuming activity on link, see Suspending and resuming activity on an individual link.

While updating link properties other than the link type, HCP temporarily suspends activity on the link.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Modifying a replication link


You use separate procedures to modify the link properties you can set when you create a link and to modify the automatic failover and failback settings for a link.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Changing link properties


To change replication link properties that you can set when you create a link:

1.In the top-level menu of the HCP System Management Console, select Services Replication.

2.On the replication Links page, click on the name of the link you want to modify.

3.On the replication link details page, click on Link.

4.In the replication Link panel, click on the Settings tab.

5.In the link Settings panel, make the changes you want.

For information on link property settings, see Creating a replication link.

6.Click on Update Link.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Changing automatic failover and failback settings


To change the automatic failover and failback settings for a replication link:

1.In the top-level menu of the HCP System Management Console, select Services Replication.

2.On the replication Links page, click on the name of the link you want.

3.On the replication link details page, click on Link.

4.In the replication Link panel, click on the Failover tab.

5.In the Failover panel, click on Automatic Failover Settings.

6.In the Automatic Failover Settings section:

oFor an active/active link or an inbound active/passive link, in the Local System section:

To enable automatic failover to the current system, select Fail over automatically. Then, in the Automatically fail over link after loss of connectivity for field, type the number of minutes HCP should wait before automatically failing over the link after a loss of connectivity to the other system involved in the link. Valid values are integers in the seven through 9,999.

To disable automatic failover to the current system, deselect Fail over automatically.

For active/passive links only, to enable automatic failback to the other system involved in the link, select Complete recovery automatically. Then, in the Automatically complete recovery when synchronization is less than field, type the number of minutes the up-to-date-as-of time for the link must be less than before HCP should automatically fail back the link. Valid values are integers in the one through 9,999.

For active/passive links only, to disable automatic failback to the other system involved in the link, deselect Complete recovery automatically.

oFor an active/active link or an outbound active/passive link, in the Remote System section:

To enable automatic failover to the other system involved in the link, select Fail over automatically. Then, in the Automatically fail over link after loss of connectivity for field, type the number of minutes HCP should wait before automatically failing over the link after a loss of connectivity to the current system. Valid values are integers in the seven through 9,999.

To disable automatic failover to the other system involved in the link, deselect Fail over automatically.

For active/passive links only, to enable automatic failback to the current system, select Complete recovery automatically. Then, in the Automatically complete recovery when synchronization is less than field, type the number of minutes the up-to-date-as-of time for the link must be less than before HCP should automatically fail back the link. Valid values are integers in the one through 9,999.

For active/passive links only, to disable automatic failback to the current system, deselect Complete recovery automatically.

7.Click on Update Settings.

For information on how automatic failover and failback work, see Failover and failback.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Considerations for deleting a replication link


These considerations apply to deleting replication links:

You can delete a replication link in the HCP System Management Console for either system involved in the link.

You can delete a replication link only while activity on the link is suspended. For information on suspending activity on a link, see Suspending and resuming activity on an individual link.

When you delete a replication link, replication on that link immediately stops. The HCP tenants and default-namespace directories on the link remain or become read-write on both systems involved in the link.

You can delete a replication link that’s included as a chained link in a second replication link. When you do this, the HCP tenants and default-namespace directories that were on the deleted link are automatically included individually in the second link.

After deleting an active/passive link, you can no longer replicate the HCP tenants and default-namespace directories included on that link to the same replica on an active/passive link unless you first delete them on the replica. If you don’t delete them, when you create a new active/passive link with the same replica, HCP doesn’t let you include them because they now exist on both systems.

If the possibility exists that you will want to replicate those tenants and directories again to the same replica on an active/passive link, you should either pause replication for the individual tenants or suspend activity on the link instead of deleting the link.

After deleting an active/passive link, you can include the HCP tenants and default-namespace directories that were included on the deleted link in a new or existing active/active link. In this case, you do not need to delete those tenants and directories from the system that was the replica for the deleted link.

A namespace can contain metadata-only objects on one or more systems in a replication topology. If you delete the only replication link that involves such a system, the data for those metadata-only objects becomes inaccessible from that system. In this case, to make the data accessible again:

oIf the deleted link was active/active, recreate the link.

oIf the deleted link was active/passive, recreate the link as an active/active link.

For information on metadata-only objects, see Metadata-only storage tiers.

You cannot delete a replication link that's part of an active or retiring erasure coding topology.

You can delete a link that's part of a retired erasure coding topology.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.

Deleting a replication link


To delete a replication link:

1.In the top-level menu of the HCP System Management Console, select Services Replication.

2.On the replication Links page, click on the name of the link you want to delete.

3.On the replication link details page, click on Link.

4.In the replication Link panel, click on the Management tab.

5.In the Management panel, click on Delete Replication Link.

6.In the Delete Replication Link section, click on Delete.

7.In response to the confirming message:

oIf any namespace being replicated on the link contains metadata-only objects on either of the systems involved in the link or if the two systems involved in the link cannot communicate with each other:

1.In the field in the message window, type YES. This value is case sensitive.

2.Click on Delete Link.

oIf no namespaces being replicated on the link contain metadata-only objects on either of the systems involved in the link and the two systems involved in the link can communicate with each other, click on Delete Link.

© 2015, 2019 Hitachi Vantara Corporation. All rights reserved.