GLYPH<SM590000> Easy Tier automatic data placement is not supported on image mode or sequential volumes. However, it supports evaluation mode for such volumes. I/O monitoring is supported and statistics are accumulated. 

GLYPH<SM590000> When a volume is migrated out of a storage pool that is managed with Easy Tier, Easy Tier automatic data placement mode is no longer active on that volume. Automatic data placement is also turned off while a volume is being migrated, even when it is between pools that have Easy Tier automatic data placement enabled. Automatic data placement for the volume is reenabled when the migration is complete. 

When the system migrates a volume from one storage pool to another, it attempts to migrate each extent to an extent in the new storage pool from the same tier as the original extent, if possible. 

GLYPH<SM590000> When Easy Tier automatic data placement is enabled for a volume, you cannot use the svctask migrateexts  CLI command on that volume. 

## 10.1.2 Implementing and tuning Easy Tier 

The Easy Tier function is enabled by default. It starts monitoring I/O activity immediately after storage pools and volumes are created. It also starts extent migration when the necessary I/O statistics are collected. 

A few parameters can be adjusted. Also, Easy Tier can be disabled on selected volumes in storage pools. 

## MDisk settings 

The tier for internal (array) MDisks is detected automatically and depends on the type of drives that are its members. No adjustments are needed. 

For an external MDisk, the tier is assigned when it is added to a storage pool. To assign the MDisk, navigate to Pools →  External Storage , select the MDisk (or MDisks) to add and click Assign . 

Note:  The tier of MDisks mapped from certain types of IBM System Storage Enterprise Flash is fixed to tier0_flash and cannot be changed. 

