Easy Tier manual processing

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Easy Tier® manual processing provides the capability to migrate volumes and merge pools, under the same DS8A00 system, concurrently with I/O operations.

With Easy Tier manual processing, you can dynamically relocate a logical volume between pools or within a pool to change the extent allocation method of the volume or to redistribute the volume across new ranks. This capability is referred to as dynamic volume relocation. You can also merge two existing pools into one without affecting the data on the logical volumes that are associated with the pools.

Enhanced functions of Easy Tier manual processing offer more capabilities. You can use manual processing to relocate your extents, or to relocate an entire volume from one pool to another pool. Later, you might also need to change your storage media or configurations. Upgrading to a new disk drive technology, rearranging the storage space, or changing storage distribution within a specific workload are typical operations that you can complete with volume relocations. Use manual processing to achieve these operations with minimal performance impact and to increase the options you have in managing your storage.

Functions and features of Easy Tier manual processing

This section describes the functions and features of Easy Tier manual processing.

Volume migration
Volume migration for restriping can be achieved by:
  • Restriping - Relocating a subset of extents within the volume for volume migrations within the same pool.
  • Rebalancing - Redistributing the volume across available ranks. This feature focuses on providing pure striping, without requiring preallocation of all the extents. This means that you can use rebalancing when only a few extents are available.
You can select which logical volumes to migrate, based on performance considerations or storage management concerns. For example, you can:
  • Migrate volumes from one pool to another. You might want to migrate volumes to a different pool that has more suitable performance characteristics, such as different disk drives or RAID ranks. For example, a volume that was configured to stripe data across a single RAID can be changed to stripe data across multiple arrays for better performance. Also, as different RAID configurations become available, you might want to move a logical volume to a different pool with different characteristics, which changes the characteristics of your storage. You might also want to redistribute the available disk capacity between pools.
    Notes:
    • When you initiate a volume migration, ensure that all ranks are in the configuration state of Normal in the target pool.
    • Volume migration is supported for standard and ESE volumes. There is no direct support to migrate auxiliary volumes. However, you can migrate extents of auxiliary volumes as part of ESE migration or rank depopulation.
    • Ensure that you understand your data usage characteristics before you initiate a volume migration.
    • The overhead that is associated with volume migration is comparable to a FlashCopy® operation that runs as a background copy.
  • Change the extent allocation method that is assigned to a volume. You can relocate a volume within the same pool but with a different extent allocation method. For example, you might want to change the extent allocation method to help spread I/O activity more evenly across ranks. If you configured logical volumes in a pool with fewer ranks than now exist in the pool, you can use Easy Tier to manually redistribute the volumes across new ranks.
    Note: If you specify a different extent allocation method for a volume, the new extent allocation method takes effect immediately.
Manual volume rebalance by using volume migration

Volume and pool rebalancing are designed to redistribute the extents of volumes within a non managed pool. This means skew is less likely to occur on the ranks.

Notes:
  • Manual rebalancing is not allowed in multiple-tier or managed pools.
  • Manual rebalancing is allowed in single-tier pools.
  • You cannot mix fixed block (FB) and count key data (CKD) drives.

Volume rebalance can be achieved by initiating a manual volume migration. Use volume migration to achieve manual rebalance when a rank is added to a pool, or when a large volume with rotate volumes EAM is deleted. Manual rebalance is often referred to as capacity rebalance because it balances the distribution of extents without factoring in extent usage. When a volume migration is targeted to the same pool and the target EAM is rotate extent, the volume migration acts internally as a volume rebalance.

Use volume rebalance to relocate the smallest number of extents of a volume and restripe the extents of that volume on all available ranks of the pool where it is located. The behavior of volume migration, which differs from volume rebalance, continues to operate as it did in the previous version of Easy Tier.
Notes: Use Easy Tier to:
  • Migrate ESE logical volumes
  • Rebalance pools by submitting a volume migration for every standard and ESE volume in a pool
  • Merge pools with virtual rank auxiliary volumes in both the source and destination pool
Pools
You can merge single-tier and multiple-tier pools. Merged pools can have 1, 2 or 3 tiers.
Rank depopulation

Easy Tier provides an enhanced method of rank depopulation, which can be used to replace old drive technology, reconfigure pools and tear down multiple-tier pools. This method increases efficiency and performance when you replace or relocate whole ranks. Use Easy Tier to affect rank depopulation on any ranks in the various volume types (ESE logical, virtual rank auxiliary, TSE repository auxiliary, SE repository auxiliary, and non SE repository auxiliary).

Use rank depopulation to concurrently stop by using one or more ranks in a pool. You can use rank depopulation to do any of the following functions:
  • Swap out old drive technology
  • Reconfigure pools
  • Tear down multiple-tier pools
  • Change RAID types
Note: Rank depopulation is supported on ranks that have extent space efficient (ESE) extents.