## Dynamic volume migration 

Dynamic volume migration or dynamic volume relocation (DVR) is a capability that is provided as part of the Easy Tier manual mode facility. 

DVR allows data that is stored on a logical volume to be migrated from its currently allocated storage to newly allocated storage while the logical volume remains accessible to attached hosts. 

The user can request DVR by using the Migrate Volume function that is available through the DS Storage Manager GUI (DS GUI) or DS CLI. DVR allows the user to specify a target extent pool and an EAM. The target extent pool can be a separate extent pool than the extent pool where the volume is located. It can also be the same extent pool, but only if it is a non-hybrid or single-tier pool. However, the target extent pool must be managed by the same DS8880 internal server. 

Important:  DVR in the same extent pool is not allowed in the case of a managed pool. In managed extent pools, Easy Tier automatic mode automatically relocates extents within the ranks to allow performance rebalancing. The Easy Tier application can also be used to manually place volumes in designated tiers within a managed pool. For more information, see DS8870 Easy Tier Application , REDP-5014. 

In the current implementation, you can only move volumes between pools of the same extent size . 

Dynamic volume migration provides the following capabilities: 

GLYPH<SM590000> The ability to change the extent pool in which a logical volume is provisioned. This ability provides a mechanism to change the underlying storage characteristics of the logical volume to include the drive class (Flash, Enterprise, or Nearline), drive RPM, and RAID array type. Volume migration can also be used to migrate a logical volume into or out of an extent pool. 

GLYPH<SM590000> The ability to specify the extent allocation method for a volume migration that allows the extent allocation method to be changed between the available extent allocation methods any time after volume creation. Volume migration that specifies the rotate extents EAM can also be used (in non-hybrid extent pools) to redistribute a logical volume’s extent allocations across the existing ranks in the extent pool if more ranks are added to an extent pool. 

Each logical volume has a configuration state. To begin a volume migration, the logical volume initially must be in the normal configuration state. 

More functions are associated with volume migration that allow the user to pause, resume, or cancel a volume migration. Any or all logical volumes can be requested to be migrated at any time if available capacity is sufficient to support the reallocation of the migrating logical volumes in their specified target extent pool. For more information, see IBM DS8000 Easy Tier (for DS8880 R8.5 or later) , REDP-4667. 

