Automatic data placement
When IBM® Easy Tier® is active on the system, Easy Tier measures the host access activity to the data on each storage extent. It also provides a mapping that identifies high activity extents, and then moves the high-activity data according to its relocation plan algorithms.
To automatically relocate the data, Easy Tier initiates the following
processes:
While it relocates volume extents, Easy Tier follows these actions:
Automatic data placement is enabled by default for storage pools with more than one tier of
storage. When you enable automatic data placement, by default all striped volumes are candidates for
automatic data placement. Image mode and sequential volumes are never candidates for automatic data
placement. When automatic data placement is enabled, I/O monitoring is undertaken for all volumes
whether or not the volume is a candidate for automatic data placement. When automatic data placement
is enabled and there is sufficient activity to warrant relocation, extents will be relocated within
a day after enablement. You can control whether Easy Tier automatic data placement and
I/O activity monitoring is enabled or disabled by using the settings for each storage pool and each
volume. Each command in the following list that can create or change the settings for storage pools
can enable or disable both Easy Tier functions. Any command that can create or change the settings for volumes can enable or disable
automatic data replacement, if automatic data replacement is enabled for the storage pool. You can
control or view automatic data placement by using the following command line interface (CLI)
commands:
- Adds a copy to an existing volume by changing a nonmirrored volume into a mirrored volume.
- Modifies the properties of the storage pool. Use this command to turn on Easy Tier evaluation mode or I/O
monitoring and to turn off Easy Tier functions on a storage pool with more than one tier of storage. Note: When automatic data placement is active on a storage pool, set a warning threshold for the storage pool. Automatic data placement cannot function if the storage pool is used 100%.
- Modifies the properties of a volume.
- Lists storage pool information.
- Lists volume information.
- Lists volume copy information.
- Creates a storage pool.
- Creates sequential, striped, or image mode volumes.
If you want to disable automatic data placement for a volume or storage pool, set the easytier attribute to off.