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Sharing TrueCopy volumes

You can share TrueCopy (TC) pair volumes with non-TC volumes. All of the software products that can be used with TC are discussed here.

Volume types that can be shared with TrueCopy

You can use other software product volumes as TrueCopy P-VOL or S-VOL, if you have those other software products.

The following table lists the types of volumes by software product and indicates whether the volume can also be used as a TC P-VOL or a TC S-VOL.

Volume type

Used as TC P-VOL?

Used as TC S-VOL?

Active flash

DP-VOL

Yes

Yes

Pool-VOL

No

No

Cache Residency Manager (VSP 5000 series)

Cache Residency Manager volume

Yes

Yes

Virtual LUN

Virtual LUN volume

Yes

Yes

Thin Image (TI) 6

P-VOL in all statuses except RCPY

Yes

Yes

P-VOL in RCPY status

No

No

V-VOL

No

No

Pool-VOL

No

No

Cross-OS File Exchange

Volume usable by both mainframe and open systems

No

No

Data Retention Utility

Volume with Read/Write attribute

Yes

Yes

Volume with Read Only attribute

Yes

Yes

Volume with Protect attribute

Yes

Yes

Volume that is disabled for use as an S-VOL

Yes

No

Dynamic Provisioning

DP-VOL

Yes

Yes

Pool-VOL

No

No

V-VOL with capacity saving enabled

Yes

Yes

Deduplication system data volume

No

No

Dynamic Tiering

DP-VOL

Yes

Yes

Pool-VOL

No

No

Global-active device (GAD)

P-VOL

No

No

S-VOL

No

No

Quorum disk

No

No

Volume with reserve attribute for S-VOL

No

No

Global storage virtualization

Volumes in a virtual storage machine1

Yes

Yes

LUN Manager

Volume to which an LU path is defined

Yes

Yes

Volume defined as a namespace for NVMe

No

No

Volume to which no LU path is defined or a volume that is not defined as a namespace for NVMe

No

No

Volume to which LUN security is applied

Yes

Yes

ShadowImage (SI)

P-VOL in PSUS (Delete pair to RCU) status

Yes

Yes7

P-VOL in COPY(RS-R)/RCPY status

No

No

SI P-VOL is also used as a UR P-VOL or S-VOL

No

No

P-VOL (none of the above)

Yes

Yes7

S-VOL in PSUS (Delete pair to RCU) status

Yes

No

S-VOL (none of the above)

No

No

Reserved volume (VSP 5000 series)

No

No

Universal Replicator (UR)

P-VOL in COPY status

No

No

P-VOL in PAIR status

Yes2, 8

No3

P-VOL in PSUS (Delete pair to RCU) status

Yes2, 8

No9

P-VOL in PSUE (pair suspended-error) status

Yes2, 8

No98

S-VOL in COPY status

No

No

S-VOL in PAIR status

No

No

S-VOL in PSUS (Delete pair to RCU) status

Yes2

No

S-VOL in SSWS status

Yes2

No

S-VOL in PSUE (pair suspended-error) status

Yes2

No

Journal Volume (VSP Gx00 models and VSP Fx00 models, VSP E series)

No

No

Universal Volume Manager

Mapped external volume

Yes

Yes

Virtual Partition Manager (VPM)

Volume belonging to the Virtual Partition Manager CLPR

Yes

Yes

Volume Migration5

Source volume (when volume migration is in progress)

Yes. (If the source volume is a P-VOL, volume migration will stop.)

Yes. (If the source volume is an S-VOL, volume migration will stop.)4

Source volume (after volume migration is finished)

Yes

Yes

Target volume

No

No

Reserved volume (VSP 5000 series)

No

No

Notes:

  1. The volume whose virtual LDEV ID is deleted cannot be used as pair volume of TC.
  2. A volume used with TC cannot be used as a volume shared with two UR pairs. For VSP 5000 series, the volume shared with two UR pairs cannot be used with TC in a 3DC multi-target or 3DC cascade configuration with the three UR sites.
  3. (VSP 5000 series) The volume can be used only when you resynchronize a TC pair or perform a CCI horc takeover operation. The volume can also be used if the applicable UR pair belongs to a journal registered by selecting 2DC Cascade for Journal Type Option in the Create Journals window.
  4. If the TC S-VOL is a DP-VOL, the TC pair cannot be created. Create the TC pair after completing volume migration or stopping the Volume Migration operation.
  5. For more information about using Volume Migration, contact customer support.
  6. (VSP 5000 series) For the node volume and the leaf volume of Thin Image, see the description of S-VOL, not P-VOL.
  7. (VSP Gx00 modelsand VSP Fx00 models, VSP E series) When both TrueCopy P-VOL and S-VOL are Dynamic Provisioning virtual volumes (DP-VOL), the TC S-VOL cannot be used as a P-VOL of a ShadowImage pair.
  8. (VSP 5000 series) Cannot be used if the TC pair belongs to a journal registered by selecting 2DC Cascade for Journal Type Option in the Create Journals window.
  9. (VSP 5000 series) The volume can be used only when you resynchronize a TC pair or perform a CCI horctakeover operation. The volume cannot be used if the UR pair belongs to a journal registered by selecting 2DC Cascade for Journal Type Option in the Create Journals window.

Cache Residency Manager (VSP 5000 series)

The volumes which set the Cache Residency Manager can be assigned as the TrueCopy pair. You can perform Cache Residency Manager operations on TC P-VOLs and S-VOLs. For more information, see the Performance Guide.

Data Retention Utility

You can create a TC pair using volumes that have been assigned the access attribute by the Data Retention Utility (DRU). However, you cannot specify a volume with the "S-VOL Disable" attribute as a TC S-VOL.

The following table shows whether a DRU volume with the specified access attribute can be used as a TC P-VOL or S-VOL.

DRU access attribute

Availability of TC P-VOL or S-VOL

P-VOL

S-VOL

Read/Write

Yes

Yes

Read Only

Yes

Yes

Protect

Yes

Yes

S-VOL Disable

Yes

No

Read Only and S-VOL Disable

Yes

No

Protect and S-VOL Disable

Yes

No

The following tables show TC volumes and status with Data Retention Utility operations that can be performed using Device Manager - Storage Navigator.

TC

Volume

PAIR

status

DRU operation

Referring

access

attribute

Changing access attribute

Read/Write

Read Only

Protect

S-VOL

Disable

P-VOL

SMPL

Yes

Yes

Yes

Yes

Yes

COPY

Yes

Yes

Yes

Yes

Yes

PAIR

Yes

Yes

Yes

Yes

Yes

PSUS

Yes

Yes

Yes

Yes

Yes

PSUE

Yes

Yes

Yes

Yes

Yes

S-VOL

SMPL

Yes

Yes

Yes

Yes

Yes

COPY

No

No

No

No

Yes

PAIR

No

No

No

No

Yes

PSUS

Yes

Yes

Yes

Yes

Yes

PSUE

Yes

Yes

Yes

Yes

Yes

The following tables show TC volumes and status with the Data Retention Utility operations that can be performed using Device Manager - Storage Navigator and CCI.

TC

Volume

PAIR

status

DRU operation

Referring

access

attribute

Changing access attribute

Read/Write

Read Only

Protect

S-VOL

Disable

P-VOL

SMPL

Yes

Yes

Yes

Yes

Yes

COPY

Yes

Yes

Yes

Yes

Yes

PAIR

Yes

Yes

Yes

Yes

Yes

PSUS

Yes

Yes

Yes

Yes

Yes

PSUE

Yes

Yes

Yes

Yes

Yes

S-VOL

SMPL

Yes

Yes

Yes

Yes

Yes

COPY

Yes

Yes

Yes

No

Yes

PAIR

Yes

Yes

Yes

No

Yes

PSUS

Yes

Yes

Yes

Yes

Yes

PSUE

Yes

Yes

Yes

Yes

Yes

Dynamic Provisioning

You can create a TrueCopy pair by specifying a DP-VOL (Dynamic Provisioning virtual volume). DP-VOLs can be assigned to both the TC P-VOL and S-VOL, or to one of them. However, the following restrictions apply:

  • A V-VOL with capacity saving enabled can be used as a P-VOL or S-VOL of a TC pair. However, a deduplication system data volume cannot be used as a P-VOL or S-VOL of a TC pair.
  • (VSP 5000 series) Data compressed or deduplicated by the capacity saving function is copied to a volume after compression and deduplication are released. The capacity saving function is not performed immediately for copied data. Before creating or resynchronizing a TC pair, make sure that the available capacity in the copy destination volume is greater than the used capacity in the copy origination volume before capacity saving. For details, see the Provisioning Guide for your storage system.
  • If you create a TC pair using a volume for which the capacity saving function is used, compressed or deduplicated data is copied. Because of this, copy or I/O performance might be degraded.
  • When the capacity saving function is used, management information is stored in a pool. As a result, there could be a difference between a P-VOL and an S-VOL in the number of used pages or licensed capacity.
  • You can use DP-VOLs that are also used in a ShadowImage pair, or in a Volume Migration migration plan. Before creating the TC pair, delete the SI pair, or disable the Volume Migration setting. After the pair is created, re-create the pair or migration plan.
  • When a DP-VOL has pages allocated to an S-VOL, used pool capacity is temporarily larger than the actual capacity because pages must be reallocated in the DP-VOL. Therefore, before creating the pair, make sure of the following:
    • DP-VOL pool capacity is sufficient.
    • Pool-VOLs that are added to a pool are not blocked. If Pool-VOLs are blocked, restore the volume status and then create the pair.
    • With capacity saving enabled in addition to assigned pages, LDEV formatting was performed on the volume you want to use as the S-VOL.
      NoteIf you create a pair without performing LDEV formatting, the initialization is performed during the copy operation, which might increase the required time for copying or might raise the processor operating rate.
    • With capacity saving enabled in addition to assigned pages, the volume you want to use as the S-VOL was set to the mode that satisfies your user requirements:
      • User requirement is to suppress the impact on the I/O performance

        The post-process mode is set.

        The S-VOL requires the pool capacity to be as large as the P-VOL because capacity saving is performed after the pair is created.

      • User requirement is to suppress the required pool capacity

        The inline mode is set.

        The required time for copying might be longer or the processor operating rate might be greater than that in the post-process mode. Consider applying the post-process mode to suppress the required time or processor operating rate.

        If you use any of the following DKCMAIN firmware versions and create a pair without performing LDEV formatting, the post-process mode is applied even if you set the inline mode. Therefore, ensure that the pool capacity is as large as the P-VOL.

        • (VSP 5000 series) Earlier than 90-05-04-xx/xx
        • (VSP 5000 series) 90-06-01-xx.xx or later, earlier than 90-06-21-xx/xx
        • (VSP E series) Earlier than 93-04-02-xx/xx
  • Regarding page and license capacity:
    • If a pair does not include a DP-VOL, volume capacity is counted toward TC license capacity. For a DP-VOL with the data direct mapping attribute, volume capacity will be counted towards TC license capacity.

      If a pair includes a DP-VOL, only the allocated page capacity of volume capacity is counted toward TC license capacity.

      However, if capacity saving is enabled, the capacity before saving is counted towards the TC licensed capacity.

      If a DP-VOL and a non-DP-VOL are included in a pair, the page capacity and/or license capacity counted in the P-VOL and the S-VOL might be different. This applies even when both P-VOL and S-VOL include DP-VOLs, because the page capacity of the P-VOL or the S-VOL changes by a relocated pool or released page or other action.

  • When you migrate data from a P-VOL in an earlier storage system to a DP-VOL S-VOL, the DP-VOL S-VOL might consume the same page capacity as the P-VOL.
  • You can expand the capacity of DP-VOLs used as TC pair volumes if the microcode version for both the primary and secondary storage systems is the following version:
    • VSP 5000 series: 90-04-04-00/00 or later
    • VSP G/F350, G/F370, G/F700, G/F900: 88-06-02-x0/00 or later
    • VSP E series: 93-02-03-x0/00 or later

    For more information about the procedure for expanding the DP-VOL capacity, see Expansion of DP-VOL capacity while keeping pair status.

For more information, see the Provisioning Guide for your storage system.

Global storage virtualization

You can create TrueCopy pairs using volumes in a virtual storage machine, but you should be aware of a couple of operational details.

You should be aware of the following when using volumes in a virtual storage machine:

  • Though HDvM - SN displays the virtual LDEV ID of a volume belonging to a virtual storage machine, make sure when running pair operations in Device Manager - Storage Navigator that you specify the physical LDEV ID of the volume.
  • A volume's virtual ID used with TrueCopy cannot be deleted.

LUN Manager

  • LUN Manager operations do not affect TC operations.
  • Volumes that are under secure ports and/or that are assigned to host groups or iSCSI targets can also be assigned to TC pairs.
  • Volumes that are assigned to TC pairs can also be assigned to secure ports and host groups or iSCSI targets for LUN Manager.
  • TC S-VOLs cannot be accessed by any UNIX/PC server host except when the pair is split.

For more information, see the Provisioning Guide for your storage system.

Performance Monitor

Performance Monitor software provides detailed information about I/O activity and hardware performance in the storage system. Storage system usage and performance data is collected and displayed by Performance Monitor. This information helps you to:

  • Identify the optimum timing for performing TC operations.
  • Determine the best locations for the TC S-VOL (for example, parity groups with less-frequently accessed volumes to avoid bottlenecks of backend activity).
  • Monitor system performance during TC operations and during testing activities.

See the Performance Guide for your storage system for more information.

ShadowImage

You can assign ShadowImage volumes to TC pairs, and you can assign TC volumes to SI pairs.

The following table shows the configurations that are possible.

TC volume

SI P-VOL

SI S-VOL

P-VOL

Yes

Yes

S-VOL

Yes

No

Note the following when sharing TC volumes with SI volumes.

  • L1 and L2 SI pairs can be shared with TC volumes. Both node and leaf S-VOLs are considered secondary volumes by TC.
  • SI is recommended for in-system copy operations. However, if SI is not installed, TC can be used to copy within the same storage system. This configuration requires at least one fibre channel or iSCSI cable loop.
  • The SI Quick Restore can be performed when the TC pair is suspended. For information about the Quick Restore operation, see the Hitachi ShadowImage® User Guide.

Configurations with ShadowImage P-VOLs

TC can share an SI P-VOL in three configurations:

  • In the following figure, the TC P-VOL also functions as an SI P-VOL. This configuration allows you to use SI for on-site data backup in case of TC failure. Or, the TC S-VOL can be used to provide remote backup of the SI P-VOL in case of an SI failure.
    Shared TC P-VOL with SI P-VOL
    GUID-C2C89227-5E54-4E88-A9F9-C2FF697E88A6-low.gif

    In this configuration, you can only delete TC pairs when the SI P-VOL status is COPY(RS-R)/RCPY. The following table shows possibilities of TC pair operations according to the SI P-VOL status.

    SI P-VOL status

    TC pair operations

    Create

    Split

    Delete

    Resync

    Switch operations between the primary and secondary sites (horctakeover)

    P-VOL specified

    S-VOL specified

    P-VOL specified

    S-VOL specified

    COPY(PD)/COPY

    COPY(SP)/COPY

    COPY(RS)/COPY

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    PAIR

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    PSUS(SP)/PSUS

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    PSUS

    PSUE

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    COPY(RS-R)/RCPY

    No

    No

    No

    No

    No

    Yes

    No

  • In the following figure, the TC S-VOL also functions as an SI P-VOL. In this configuration, SI provides another (or several more) backup copies of a TC P-VOL.

    When an SI P-VOL is shared with the TC S-VOL, the write operation to the TC P-VOL takes a longer time than normal. This is especially true when the SI pair is in the PSUS(SP)/PSUS status and is caused by the SI copying process. The processing time is increased by the processing time for SI added to the normal TC unit copy processing. The processing time might be increased by dozens of milliseconds with the addition of SI.

    Shared TC S-VOL with SI P-VOL
    GUID-DB303307-C21B-460B-8CAE-DC0E00CE3684-low.gif

    In this configuration, you can only delete TC pairs when the SI P-VOL status is COPY(RS-R)/RCPY. The following table shows possibilities of TC pair operations according to the SI P-VOL status.

    SI P-VOL status

    TC pair operations

    Create

    Split

    Delete

    Resync

    Switch operations between the primary and secondary sites (horctakeover)

    P-VOL specified

    S-VOL specified

    P-VOL specified

    S-VOL specified

    COPY(PD)/COPY

    COPY(SP)/COPY

    COPY(RS)/COPY

    Yes*

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    PAIR

    Yes*

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    PSUS(SP)/PSUS

    Yes*

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    PSUS

    PSUE

    Yes*

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    COPY(RS-R)/RCPY

    No

    No

    No

    No

    No

    Yes

    No

    * When the P-VOL and the S-VOL of a TrueCopy pair are used as the DP-VOL of Dynamic Provisioning, if you share the P-VOL of a ShadowImage pair with the S-VOL of the TrueCopy pair, you must delete the ShadowImage pair before creating the TrueCopy pair. For details, see Dynamic Provisioning .
  • In the following figure, the configurations shown in the previous two figures are combined. Both the TC P-VOL and S-VOL function as SI P-VOLs, providing multiple copies at the primary and secondary sites.
    Shared TC P-VOL, S-VOL with multiple SI P-VOLs
    GUID-6978309D-5DE6-440C-A1BF-39BDA89D435B-low.gif

    In this configuration, you can only delete TC pairs when the SI P-VOL status is COPY(RS-R)/RCPY. The following table shows possibilities of TC pair operations according to the SI P-VOL status.

    SI P-VOL status

    TC pair operations

    Create

    Split

    Delete

    Resync

    Switch operations between the primary and secondary sites (horctakeover)

    P-VOL specified

    S-VOL specified

    P-VOL specified

    S-VOL specified

    COPY(PD)/COPY

    COPY(SP)/COPY

    COPY(RS)/COPY

    Yes*

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    PAIR

    Yes*

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    PSUS(SP)/PSUS

    Yes*

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    PSUS

    PSUE

    Yes*

    Yes

    Yes

    Yes

    Yes

    Yes

    Yes

    COPY(RS-R)/RCPY

    No

    No

    No

    No

    No

    Yes

    No

    *(VSP E series) If the TC P-VOL and TC S-VOL are DP-VOLs, the TC S-VOL cannot be used as the SI P-VOL.

Configurations with ShadowImage S-VOLs

In the following figure, an SI S-VOL also functions as a TC P-VOL. This configuration requires that the SI pair is split before the TC pair is created.

Shared SI S-VOL with TC P-VOL
GUID-3F2EBAF9-B8CD-466A-B5C9-664299973601-low.gif

In this configuration, before creating a TC pair, you must set the SI in the PAIR status, split the SI pair, and then set it in the PSUS status. The following table shows possibilities of TC pair operations according to the SI S-VOL status.

SI S-VOL status

TC pair operations

Create

Split

Delete

Resync

Switch operations between the primary and secondary sites (horctakeover)

P-VOL specified

P-VOL specified

P-VOL specified

P-VOL specified

COPY(PD)/COPY

COPY(SP)/COPY

COPY(RS)/COPY

No

No

No

No

No

Yes

No

PAIR

No

No

No

No

No

Yes

No

PSUS(SP)/PSUS

No

No

No

No

No

Yes

No

PSUS

PSUE

Yes

Yes

Yes

Yes

Yes

Yes

No

COPY(RS-R)/RCPY

No

No

No

No

No

Yes

No

Status reporting and data currency

The following table shows the pair status that is reported for different combinations of shared volumes.

Number of TC pairs

Number of SI S-VOLs

Pair status

0

0

It does not display in pair list.

0

1

SI pair status

0

2 or more

SI pair status for the S-VOL with lowest LUN.

1

0

TC pair status

1

1

TC pair status

1

2 or more

TC pair status

  • TC pair status is reported to the host if you query the TC P-VOL or S-VOL. To obtain the SI pair status, query the SI P-VOL pair.
  • SI supports multiple S-VOLs for each of its P-VOLs, but when you issue a pair status query, the status is returned only for the pair whose S-VOL has the lowest LUN. To check pair status for the other S-VOLs, direct a host query to the specific S-VOL using the S-VOL's LUN in the host command.

    Device Manager - Storage Navigator displays the status of all S-VOLs.

The following table shows when data is current on a shared TC/SI volume based on the pair statuses.

TC pair status

SI pair status

COPY (PD)/COPY

PAIR

COPY (SP)/COPY

PSUS

COPY (RS)/COPY, COPY(RS-R)/RCPY

PSUE

COPY

Not Current

Not Current

Not Current

Current

Not Current

Not Current

PAIR

Not Current

Not Current

Not Current

Current

Not Current

Not Current

PSUS (Delete pair to RCU)/PSUE (pair suspended-error)

Not Current

Current

Current

Current

Current

Not Current

Universal Replicator

TC and Universal Replicator can share the same pair volumes. Using a combined TC and Universal Replicator configuration can extend disaster recovery options to a third data center.

Like TC, a Universal Replicator pair maintains a copy of the production volume in a second location. However, unlike TC, the Universal Replicator S-VOL is asynchronous, and the secondary system can be located much greater distances from the primary and secondary TC sites.

Creating both a TC and a Universal Replicator backup ensures that a copy in a third location is available in the event that the primary site or one of the systems fails.

Note3DC multi-target configuration and 3DC cascade configuration with TC and UR are supported only by VSP E series, VSP G900, and VSP F900.

Configurations consisting of TC and Universal Replicator pair volumes are covered extensively in the Hitachi Universal Replicator User Guide.

Virtual LUN

Virtual LUN volumes can be assigned to TC pairs, but there are restrictions.

The following are restrictions:

  • The S-VOL must have the same capacity as the P-VOL.
  • When performing Virtual LUN operations on an existing TC P-VOL or S-VOL, you must release the pair first to return the volume to SMPL status.

For more information, see the Provisioning Guide for your storage system.

Volume Migration

TC volumes can be used as Volume Migration volumes when pairs are in certain statuses.

The following table specifies the status when TC volumes can be used.

Volume/pair status

Used as Volume Migration volume?

P-VOL/S-VOL in COPY status

No

P-VOL/S-VOL in PAIR status

Yes

P-VOL/S-VOL in PSUS status

Yes

Restrictions to using a TrueCopy volume as a Volume Migration volume

There are certain restrictions when a TC volume in PAIR status is used as a Volume Migration volume.

The following restrictions must be followed:

  • Set I/O rates less than 50 IOPS while migrating volumes. If the I/O rate is more than 50 IOPS, volumes might not be migrated.
  • If a data path failure occurs, remove the failure and then migrate the volume.
  • If an external volume or a DP-VOL is used, information from before the volume was migrated is displayed in the secondary system Device Manager - Storage Navigator window. If the Volume Migration is completed and the TC pair is split and resynchronized, the volume's information is updated.
  • Do not migrate a P-VOL and S-VOL at the same time. If you do, a host I/O timeout error can occur.
  • Do not change the status of a volume during migration. If you do, the status might not change.