Implementing capacity saving

Enabling capacity saving on DP-VOLs

Use this procedure to enable the capacity saving function (compression, or deduplication and compression) on an existing DP-VOL. If the DP-VOL is in a Dynamic Tiering pool, you cannot enable the capacity saving function.

Requirements for enabling deduplication on a DP-VOL:

The dedupe and compression license must be installed.
The deduplication function must be enabled on the pool.
The pool must not be blocked.
A sufficient number of cache management devices must be available.
The LDEV status of the DP-VOL must be Normal.
The capacity saving status of the pool must not be Deleting Volume, Failed, or Rehydrating.
Data Direct Mapping must be disabled.
Full Allocation must be disabled.
The DP-VOL must not be used as a Universal Replicator journal volume.
If you create DP-VOLs of which the capacity saving setting is Deduplication and Compression, the pool must not have been deleted from the Deduplication System Data Volume (Data Store).

Before you begin

The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

Click Storage Systems, and then expand the Storage Systems tree.
Click Logical Devices.
In the LDEVs pane, select an LDEV ID, and click Edit LDEVs.
In the Edit LDEVs window, click Capacity Saving, and then select either Compression or Deduplication and Compression.

CautionIf you enable Deduplication and Compression on a DP-VOL, you will not be able to change the setting from Deduplication and Compression to Compression later.
Note
- If the LDEV status of a deduplication system data volume in the pool is other than Normal, Deduplication and Compression cannot be selected.
- If the first DP-VOLs of which the capacity saving setting is Deduplication and Compression are created in a pool, then the deduplication system data volumes are automatically created.
Click Finish. The Confirm window appears.
In the Task Name text box, type a unique name for the task or accept the default.

You can enter up to 32 ASCII characters and symbols, with the exception of: \ / : , ; * ? " < > |. The value "date-window name" is entered by default.
Click Apply.
If the Go to tasks window for status check box is selected, the Tasks window appears.

Verifying the capacity saving effect with Storage Navigator or Command Control Interface

You can verify the capacity saving effect for each pool.

The following table shows items indicating of the saving effect.

Item in the Pools window		Command item		Description
Large category or Item	Item	Command	Item	Description
Capacity	Used	raidcom get pool -key fmd	(Not Available)	Pool used capacity. As for CCI, a free capacity (ACT_AV(MB)) is displayed.
Capacity	Used (%)	raidcom get pool -key fmd	U(%)	Pool used capacity rate
Data Volumes Used Capacity	(None)	raidcom get pool -key total_saving	DATAVOL_USED(BLK)	Total used capacity of DP-VOLs
Saving Effect (Capacity saving effected by both of the capacity saving function and accelerated compression function.)	Saving Ratio		SES(%)	Ratio of the pool used capacity (#1) against the total used capacity of DP-VOLs (#3).
	Saving		SE_SAVING(BLK)	Saved capacity (= the total used capacity of DP-VOLs (#3) - the pool used capacity (#1))
Software Saving (Saving effected by the capacity saving function)	Saving Ratio	raidcom get pool -key software_saving	PLS(%)	The saved ratio with the capacity saving function.
	Compression Ratio		(Not Available)	The saved ratio with the compression function. As for CCI, a data capacity before compression (PRE_CMP_USED(BLK)) is displayed.
	Deduplication Ratio		(Not Available)	The deduplication ratio with the deduplication function. As for CCI, a data capacity before deduplication (PRE_DDP_USED(BLK)) is displayed.
	Saving		PL_SAVING(BLK)	The saved capacity with the capacity saving function. (=Compression (#10) + Deduplication (#11) + Reclaim (#12) - System Data (#13))
	Compression		CMP(BLK)	The saved capacity with the compression function.
	Deduplication		DDP(BLK)	Deduplicated capacity
	Reclaim		RECLAIM(BLK)	The reclaimed capacity.
	System Data		SYSTEM(BLK)	The system data capacity (= Meta data capacity + Garbage data capacity).
	Used (Pre Processed Data)		PL_PRE_USED(BLK)	The data capacity before performing of the capacity saving function.
FMD Saving (Saving effected by the accelerated compression function)	Compression Ratio	raidcom get pool -key fmd	(Not Available)	The saved ratio with the accelerated compression function. As for CCI, a zero pages reclaimed data capacity before performing of the accelerated compression function deduplication (FMD_LOG_USED(BLK)) is displayed.
	Saving			The saved capacity with the accelerated compression function.
	Compression			The compressed capacity with the accelerated compression function.
	Reclaim			The reclaimed capacity with the accelerated compression function.
FMD Capacity	Used		FMD_ACT_USED(BLK)	The used capacity after compressed with FMD.
Logical FMD Capacity	Used		FMD_PLV_USED(BLK)	The used capacity before compressed with FMD.

Capacity saving status

When you reference the capacity saving status--the status for the capacity saving-enabled DP-VOL--you can verify the processing progress of the capacity saving function or the integrity of data.

The following table indicates the statuses of the capacity saving status.

Capacity saving status	Description	Approximate time to change to the next status	Can perform the host I/O operation?
Disabled	The capacity saving function is disabled.	Not available	Yes
Enabling	To enable the capacity saving function, the corresponding information about the capacity saving function is being initialized.	From few seconds to minutes	Yes
Enabled	The capacity function is being enabled.	Not available	Yes
Rehydrating	The capacity saving function is being changed to disable.	From few hours to few days	Yes
Deleting Volume	The capacity saving-enabled DP-VOL which is formatted is being deleted.	From few seconds to few minutes¹	No²
Deleting Volume (nn %)	The capacity saving-enabled DP-VOL is being deleted.	From few minutes to few hours	Yes
Failed	The integrity of meta data cannot be guaranteed. This status occurs when The shared memory is volatilized and the storage system is restarted.	Not available	Yes, only reading.
Notes: ¹ The formatting LDEV operation takes time for several minutes or hours. The capacity saving status of Enabled is displayed while performing of the formatting LDEV operation. ² If I/Os are issued to the formatted DP-VOL enabled with the capacity saving, the DP-VOL deletion fails. If the deletion fails, retry by formatting the LDEV, and then delete the DP-VOL.

The following figure describes the transition of the capacity saving status.

Allowed operation for each capacity saving status

The following table indicates the available DP-VOL (LDEV) operations for each of the capacity saving status.

DP-VOL (LDEV) operation		Can the operation be performed in each of the capacity saving status?
DP-VOL (LDEV) operation		Disabled	Enabling	Enabled	Rehydrating	Deleting Volume	Failed	Deleting Volume (nn %)
Changing of the capacity saving setting	Before: Disabled After: Compression or Deduplication and Compression	Yes (The status is changed from Enabling to Enabled after performing the operation)	Yes	No	No	No	No	No
	Before: Compression or Deduplication and Compression After: Disabled	Yes	Yes (The status is changed from Rehydrating to Disabled after performing the operation)	Yes (The status is changed from Rehydrating to Disabled after performing the operation)	Yes	No	No	No
	Before: Compression After: Deduplication and Compression	No	No	Yes	No	No	No	No
Adding LUN path	Yes	Yes	Yes	Yes	Yes	No	Yes	No
Expanding DP-VOL capacity		Yes	Yes	Yes	Yes	Yes	Yes	No
Blocking DP-VOL		Yes	Yes	Yes	Yes	Yes	Yes	Yes
Restoring DP-VOL		Yes	Yes	Yes	Yes	Yes	Yes	No
Formatting DP-VOL	For DP-VOLs whose capacity saving setting is Compression	Yes	Yes	Yes	Yes	Yes	Yes¹ (The status is changed to Enabled after performing the operation)	Yes¹ (The status is changed to Enabled after performing the operation)
Formatting DP-VOL	For DP-VOLs whose capacity saving setting is Deduplication and Compression	Yes	Yes	Yes	Yes	Yes	No²	No²
Deleting DP-VOL	For the formatted DP-VOLs	Yes	Yes (The status is changed from Deleting Volume to Disabled after performing the operation)	Yes (The status is changed from Deleting Volume to Disabled after performing the operation)	No	Yes	No	Yes
Deleting DP-VOL	For the un-formatted	Yes	Yes (The status is changed to Deleting Volume (nn %) after performing the operation)	Yes (The status is changed to Deleting Volume (nn %) after performing the operation)	Yes (The status is changed to Deleting Volume (nn %) after performing the operation)	Yes (The status is changed to Deleting Volume (nn %) after performing the operation)	No	Yes
I/Os from a host		Yes	Yes	Yes	Yes	No	Yes (Read only)	Yes
Notes: ¹ If the setting of the capacity saving is Disable, the status changes to Compression after the operation. ² If you want to format the volume, perform the Initialize Duplicated Data.

Monitoring performance when capacity saving is in use

When your site implements capacity saving with deduplication and compression, you'll need to monitor peformance. If there are performance issues, there are steps you can take to resolve them.

The following table outlines the best practice points for items that can be monitored when deduplication and compression is used.

Monitored item	Description
Performance	Verify the throughput for DRD-VOLs: Throughput for each DRD-VOL Total throughput for DRD-VOLs belonged to the same MP-Unit. Total throughput for DRD-VOLs in a storage system. When the performance requirements are not met, either change the capacity saving setting or expand the pool capacity.
Pool capacity monitoring	Check whether the used pool capacity exceeds the threshold. When the capacity exceeds the threshold, the amount of system data (Amount of garbage data) is checked. When the amount of garbage data is small, expand the pool capacity.

Monitored item

Description

Performance

Verify the throughput for DRD-VOLs:

Throughput for each DRD-VOL
Total throughput for DRD-VOLs belonged to the same MP-Unit.
Total throughput for DRD-VOLs in a storage system.

When the performance requirements are not met, either change the capacity saving setting or expand the pool capacity.

Pool capacity monitoring

Check whether the used pool capacity exceeds the threshold.

When the capacity exceeds the threshold, the amount of system data (Amount of garbage data) is checked.

When the amount of garbage data is small, expand the pool capacity.

The following chart provides a task flow for detecting a performance issue and troubleshooting it by checking the capacity saving information.

Following are details for steps 1-5 of the performance assessment workflow:

Identify the pools or the volumes whose performance is insufficient. To find performance degradation in the host and check if the storage system has a problem, check if customer performance requirements are met. When one of the following conditions is met, there is a performance issue. Go to step 2:
- Throughput required by user is greater than the current throughput
- Average write throughput of DRD-VOL in the operation cycle is greater than the garbage collection performance of each DRD-VOL
- Average write throughput of each MP unit in the operation cycle is greater than the garbage collection performance of each MP unit
- Average write throughput of each system in the operation cycle is greater than the garbage collection performance of each system
Check the settings for the capacity saving function. When insufficient performance is detected, check if the settings are correct. If they are correct, go to step 3.
- If the capacity saving setting is set to Compression or Deduplication or Compression by mistake, disable the capacity saving setting.
- If the capacity saving mode is set to Inline by mistake, change it to Post process. For details how to change the capacity saving mode, see Command Control Interface Command Reference.
Check if the used pool capacity exceeds the threshold. Check if the Pool Usage exceeds the warning threshold of the pool. If the pool usage exceeds the threshold, a SIM is issued. When performance is insufficient--even if the settings are as designed--it is likely that the pool capacity will soon be full, and garbage collection is prioritized over I/O.
- If the threshold is exceeded, go to step 4.
- If the threshold is not exceeded, go to step 5.
Check the percentage of the amount of system data. Check [the amount of system data](divided by the amount of garbage data)].
- When the percentage of system data in the used pool capacity is higher than 10%:
  If you know that garbage data is increased only temporarily, and time required for recovering the performance is acceptable, wait until the performance is recovered. If it is not acceptable, expand the pool capacity.
  
  When the percentage of system data in the used pool capacity is higher than 10%, if garbage data is collected by garbage collection, the pool usage is lower than the threshold. When it is lower than the threshold, the priority of garbage collection is lowered, and I/O performance is recovered.
- When the percentage of system data in the used pool capacity is lower than 10%:
  To prioritize I/O processing, expand the pool capacity. Although the garbage data that should be collected is small, the priority of garbage collection is high.
Decide whether the capacity saving function should be used:
- When garbage collection is not effective, and performance is not sufficient, dedupe and compression cannot be applied to the volume. If there is any volume for which the capacity saving setting can be disabled, disable it.
- The used capacity of the pool increases when the capacity saving setting is disabled. Confirm in advance that the pool has enough free capacity.

About DRD-VOLs and initializing duplicated data

When a DRD-VOL whose capacity saving setting is Deduplication and Compression and deduplication system data volume belongs to a specified pool, you can use the Initialize Duplicated Data function to discard duplicate data in the pool.

Preparing to initialize duplicated data

The Initialize Duplicated Data function initializes the status of the capacity saving function for a pool. You can implement it either as a command from Storage Navigator or from Command Control Interface.

When the Initialize Duplicated Data function is used, data in a DRD-VOL that has duplicate data in the pool is forcibly discarded.

Before using Initialize Duplicated Data, check and complete the following, as necessary:

Back up necessary data
Recover pools in the event of a RAID level failure (Drive failure exceeding drive redundancy)
Initialize after shared memory data volatilization has been caused by a forced power outage

The following table lists the requirements for using Initialize Duplicated Data.

Item	Specification
Specified range	Per pool
Target	DRD-VOL whose capacity saving setting is Deduplication and Compression* and deduplication system data volume (both fingerprint and data store) that belong to the specified pool
Status after performing it	The deduplication system data volume (fingerprint) that was blocked before performing it becomes the normal status. DRD-VOL and deduplication system data volume (data store) that were blocked before performing it remain blocked. To restore them to the normal status, perform LDEV format.
Execution time	It takes one minute per total capacity 40 TB of the target volumes. Execution time = 5[min.] + ↑(Total capacity [TB]/40[TB])↑ ↑()↑: The value enclosed in ↑()↑ must be rounded up to the nearest whole number. (Example) When the capacity is 100 TB, the execution time is calculated as follows: 5+↑(100/40)↑ = 5+↑2.5↑= 8[min.]
*To initialize DRD-VOLs for which the capacity saving settings are “Deduplication and Compression” and “Compression”, you must set the system option mode 1115 to ON in advance. For details about system option modes, contact customer support.

NoteWhen issues occur while DRD-VOLs are being used, you can resolve them by following the solutions for SIM or messages. For troubleshooting, see Troubleshooting Dynamic Provisioning or GUID-EBD94445-2E52-4432-97A6-D0BE7D054357#GUID-EBD94445-2E52-4432-97A6-D0BE7D054357.

Initializing all deduplication-enabled DP-VOLs in a pool

You can restore DP-VOLs whose capacity saving status is Failed by initializing all DP-VOLs of which deduplication is enabled in a pool.

When you initialize all DP-VOLs of which deduplication is enabled in a pool, all deduplication system data volumes are also initialized.

NoteIf you initialize duplicated data for the pool that has DP-VOLs for which the capacity saving setting is Disabled and Deduplication Data is Enabled, the capacity saving setting for the DP-VOLs might become Deduplication and compression. Therefore, verify the capacity saving setting of DP-VOLs after the formatting operation completes.

Before you begin

Because this procedure deletes all user data in the deduplication-enabled DP-VOLs, back up all affected DP-VOLs in advance.
The Storage Administrator (Provisioning) role is required to perform this task.

Procedure

Click Storage Systems, expand the Storage Systems tree, then select the pool.
Click the Virtual Volumes tab.
Block DP-VOLs that are associated with the pool in the following order:
1. DP-VOLs whose Deduplication Data is Enabled.
2. Deduplication System Data Volume.
Click More Actions, and select Initialize Duplicated Data.
Click Apply.
If the Go to tasks window for status check box is selected, the Tasks window displays.
Because the status of DP-VOLs that are initialized in the duplicated data is Blocked, format DP-VOLs in the following order:
1. Deduplication System Data Volume (data store).
2. DP-VOLs whose Deduplication Data is Enabled.

Terminating the usage of capacity saving

When your site no longer needs to to use capacity saving, you can end the usage in one of two ways.

Following are the options for terminating the use of capacity saving:

Remove all DRD-VOLs
Change the capacity saving setting from DRD-VOLs to DP-VOLs
When you disable the capacity saving setting for all DRD-VOLs, they are restored to normal DP-VOLs.

Removing DRD-VOLs

The following chart outlines the task flow for removing DRD-VOLs.

Even if a DRD-VOL with Deduplication and Compression enabled is removed, duplicate data might be kept in the pool. The free pool capacity is not always increased.
You can delete a DRD-VOL by using the Delete LDEVs window. The LDEV removal operation might take a few hours. You cannot cancel LDEV removal.
With LDEV removal, even after the operation is complete, volume exists. The capacity saving status of volumes is changed to Deleting Volume, and the progress is displayed.

Disabling capacity saving settings

The following chart outlines the task flow for disabling capacity saving settings.

You can disable the setting using the Edit LDEVs window.
When the capacity saving setting is disabled, data to which compression/deduplication was applied is decompressed, and the used capacity of the pool increases. Before disabling it, make sure that the pool has a free capacity to be used by DP-VOL for DRD-VOL for which you want to disable it.
When the capacity saving setting is being disabled, [Rehydrating] is displayed as Capacity Saving Status.
Even if the capacity saving setting is being disabled, I/O can continue. You cannot cancel disabling it or enable it again.
The processing time of disabling the capacity saving setting takes long because of data decompression. You can check the progress from Storage Navigator or Command Control Interface. The disabling processing time increases depending on the used capacity of virtual volume. The disabling processing time changes according to the storage system configuration, data layout, and data content.

Next steps

Resolve issues with deduplicated and compressed pools and volumes

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