Easy Tier acceleration mode

You can change the mode rates of extent migrations through the IBM® Easy Tier® function and pool balancing functions.

Normally, your system runs with the Easy Tier accelerated mode set to off. This system default rate ensures that migrations do not affect system performance.

To view the currently configured value, enter the lssystem command. The default view for easy_tier_acceleration is off. The maximum rate of extent migrations in normal mode (the system default) is 12 GB per 5 minutes. If easy_tier_acceleration is set to on, the maximum migration rate is 48 GB per 5 minutes. The migration rate of 48 GB per 5 minutes in accelerated mode cannot always be guaranteed.

You can use the chsystem command to turn on accelerated mode and extend the limit of the migration rate from 12 GB per 5 minutes to 48 GB per 5 minutes:

chsystem -easytieracceleration on

You can return to the rate of 12 GB per 5 minutes by turning off the accelerated mode:

chsystem -easytieracceleration off

You can also temporarily enable the accelerated mode to rapidly use new capacity, such as in the following examples:

You added more capacity to an existing storage pool either by adding to an existing tier or by adding a tier to the pool. When you enable the accelerated mode, the system can quickly spread the existing volumes into the new capacity.
You are migrating multiple volumes between pools, and the target pool has more tiers than the source pool. Volume migration between storage pools preserves the tier of the volume's extents. When you enable the accelerated mode, the system can quickly take advantage of the additional tiers in the target pool.

To avoid the possibility of performance issues that are caused by overloading the managed disks, use the accelerated mode during periods of reduced system activity.