IBM DS8700, Введение и руководство по планированию

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v Manual rebalancing is not allowed in hybrid or managed pools.
v
Manual rebalancing is allowed in homogeneous pools.
v 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 the latest enhancements to Easy Tier to:
v Migrate ESE logical volumes
v
Perform pool rebalancing by submitting a volume migration for every
standard and ESE volume in a pool
v Merge extent pools with virtual rank auxiliary volumes in both the
source and destination extent pool
Extent pools
You can manually combine two existing extent pools with homogeneous or hybrid
disks into a single extent pool with SSD drives to use auto mode. However, when
merged pools are managed by Easy Tier, extents from SSD, SAS Enterprise, and
Nearline SAS are managed as a three-tier storage hierarchy.
An extent pool with any mix of SSD, SAS Enterprise, and Nearline SAS drive
classes are managed by Easy Tier in automatic mode, for situations in which:
v SSDs are located in the top tier for both DS8800 and DS8700.
v
There are three tiers composed of SSD, SAS Enterprise or Nearline SAS in a
DS8800. For a DS8700, the three tiers are SSD, FC, and SATA.
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 hybrid pools.
This method increases efficiency and performance when replacing or relocating
whole ranks. Use the latest enhancements to Easy Tier to perform 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 using one or more ranks in a pool. You
can use rank depopulation to perform any of the following functions:
v Swap out old drive technology
v
Reconfigure pools
v Tear down hybrid pools
v
Change RAID types
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Introduction and Planning Guide