IBM DS8880 Series, Introduction And Planning Manual

Page: 76 / 244

Warm demotion
Active data that has larger bandwidth is demoted to the next lowest tier.
Warm demotion is triggered whenever the higher tier is over its bandwidth
capacity. Selected warm extents are demoted to allow the higher tier to
operate at its optimal load. Warm demotes do not follow a predetermined
schedule.
Warm promotion
Active data that has higher IOPS is promoted to the next highest tier.
Warm promotion is triggered whenever the lower tier is over its IOPS
capacity. Selected warm extents are promoted to allow the lower tier to
operate at its optimal load. Warm promotes do not follow a predetermined
schedule.
Manual volume or pool rebalance
Volume rebalancing relocates the smallest number of extents of a volume
and restripes those extents on all available ranks of the extent pool.
Auto-rebalancing
Automatically balances the workload of the same storage tier within both
the homogeneous and the hybrid pool that is based on usage to improve
system performance and resource use. Use the auto-rebalancing functions
of Easy Tier to manage a combination of homogeneous and hybrid pools,
including relocating hot spots on ranks. With homogeneous pools, systems
with only one tier can use Easy Tier technology to optimize their RAID
array usage.
Rank depopulations
Allows ranks that have extents (data) allocated to them to be unassigned
from an extent pool by using extent migration to move extents from the
specified ranks to other ranks within the pool.
Thin provisioning
Support for the use of thin provisioning is available on ESE and standard
volumes. The use of TSE volumes (FB and CKD) is not supported.
Easy Tier provides a performance monitoring capability, regardless of whether the
Easy Tier feature is activated. Easy Tier uses the monitoring process to determine
what data to move and when to move it when you use automatic mode. You can
enable monitoring independently (with or without the Easy Tier feature activated)
for information about the behavior and benefits that can be expected if automatic
mode were enabled.
Data from the monitoring process is included in a summary report that you can
download to your local system.
VMware vStorage API for Array Integration support
The storage system provides support for the VMware vStorage API for Array
Integration (VAAI).
The VAAI API offloads storage processing functions from the server to the storage
system, reducing the workload on the host server hardware for improved
performance on both the network and host servers.
The following operations are supported:
Atomic test and set or VMware hardware-assisted locking
The hardware-assisted locking feature uses the VMware Compare and
64
DS8880 Introduction and Planning Guide