Moving volumes to a data reduction pool

The system supports migrating existing volumes to a data reduction pool with volume mirroring or through remote-copy for volumes that already use mirroring, such as in HyperSwap configurations. Hosts I/O operations to the volume are not disrupted during migration.

Data reduction can increase storage efficiency and performance and reduce storage costs, especially for flash storage. Data reduction reduces the amount of data that is stored on external storage systems by reclaiming previously used storage resources that are no longer needed by host systems. The system supports data reduction pools, which contain thin-provisioned or compressed volumes as well as specific volumes that track when space is freed from hosts. When space is freed from hosts, the process is called unmapping. Unmap is a set of SCSI commands that hosts use to indicate that allocated capacity is no longer required on a target volume. The freed space can be collected and reused on the system without the reallocation of capacity on the external storage system. When a system uses either compressed or thin-provisioned volumes or a combination of these volume types in data reduction pools, hosts can automatically allocate and unmap storage without intervention. Reclaimed capacity can be used for other volumes, which more efficiently uses existing storage resources. When a data reduction pool is created, the system monitors the pool for reclaimable capacity from host unmap operations. This capacity can be reclaimed by the system and redistributed into the pool. To maximize space within the pool, create volumes that use thin provisioning or compression within the data reduction pool.

You can move volumes in existing pools to data reduction pools to simplify management of reclaimed capacity. The data reduction pool tracks the unmap operations of the hosts and reallocates capacity automatically. The system supports volume mirroring to create a copy of the volume in a new data reduction pool. This method creates a copy of the volume in a new data reduction pool and does not disrupt host operations.

Using the management GUI

To migrate volumes to a data reduction pool, select complete theses steps:

Create an empty data reduction pool by completing these steps:
1. In the management GUI, select Pools > Pools.
2. On the Pools page, click Create.
3. On the Create Pool page, enter a name of the pool and select Data Reduction.
4. Click Create.
Create a copy of the compressed or thin-provisioned volume by completing these steps:
1. In the management GUI, select Pools > Volumes by Pools.
2. Select the existing pool that contains the volumes you want to migrate to the data reduction pool. Right-click the volume and select Add Volume Copy.
3. On the Add Volume Copy page, select the data reduction pool to create a copy of the volume. Copy 1 is created in the original pool, while copy 2 is created in the data reduction pool. Ensure that either thin-provisioning or compressed is selected for the capacity savings.
4. Click Add.
5. Ensure that the copies are synchronized before you proceed to the next steps. Synchronization takes only a few minutes to complete. On the Volumes page, ensure that Yes is displayed for both copies in the Synchronized column.
If the volume copies are no longer needed, delete them by completing these steps:
1. In the management GUI, select Volumes > Volumes.
2. Right-click the volume copy and select Delete.
3. Click Yes to confirm the deletion.

Using the command-line interface

To migrate volumes to a data reduction pool in the command-line interface,complete these steps:

To create an empty data reduction pool, enter the following command:
```
mkmdiskgrp -pool pool_name -ext extent_size -datareduction yes
```
Where pool_name is the name of the pool and extent_size is the extent size of the pool.
To create copies of the volume in the data reduction pool, enter the following command:
```
addvdiskcopy -mdiskgrp mdisk_group_name_list -compressed -rsize disk_size -autoexpand vdisk_name
```
```
addvdiskcopy -mdiskgrp mdisk_group_name_list -rsize disk_size -autoexpand vdisk_name
```
Where mdisk_group_name_list specifies the name of the data reduction pool created in #svc_icmigratedataredtoreg/d9327e121 in which the copies reside and disk_size is an integer value in megabytes (MB). The vdisk_name variable is the name of the volume that is being copied.
To ensure that the copies of the volume are synchronized, enter the following command:
```
lsvdisk vdisk_name
```
Where vdisk_name is the name of the volume that contains the copies. In the command output, verify that the sync value is set to yes, which indicates that the volume copies are synchronized.
If the volume copies are no longer needed, enter the following command:
```
rmvdiskcopy -copy copy_idvdisk_name
```
Where copy_id is the system-assigned identifier for the volume copy and vdisk_name is the name of the original volume.