Chapter 10. Advanced features for storage efficiency 411
Example 10-1   Listing and changing tiers for MDisks (partially shown)
IBM_Storwize:ITSOV7K:superuser>lsmdisk
id name   status mode      mdisk_grp_id ... tier            encrypt 
1  mdisk1 online unmanaged              ... tier0_flash     no      
2  mdisk2 online managed   0            ... tier_enterprise no              
3  mdisk3 online managed   0            ... tier_enterprise no   
<...>  
IBM_Storwize:ITSOV7K:superuser>chmdisk -tier tier1_flash mdisk2
IBM_Storwize:ITSOV7K:superuser>
For an external MDisk, the system cannot calculate its exact performance capabilities, so it 
has several predefined levels. In rare cases, statistics analysis might show that Easy Tier is 
overusing or under-using an MDisk. If so, levels can be adjusted only by using the CLI. Use 
chmdisk with -easytierload parameter. To reset Easy Tier load to system-default for chosen 
MDisk, use -easytier default, as shown in Example 10-2. 
Example 10-2   Changing Easy Tier load
IBM_Storwize:ITSOV7K:superuser>chmdisk -easytierload default mdisk2
IBM_Storwize:ITSOV7K:superuser>
IBM_Storwize:ITSOV7K:superuser>lsmdisk mdisk2 | grep tier
tier tier_enterprise
easy_tier_load high
IBM_Storwize:ITSOV7K:superuser>
To list the current Easy Tier load setting of an MDisk, use lsmdisk with MDisk name or ID as 
a parameter.
Storage pool settings
When storage pool (either standard pool or Data Reduction Pool) is created, Easy Tier is 
switched on by default. The system automatically enables Easy Tier functions when the 
storage pool contains an MDisk from more than one tier. It also enables automatic 
rebalancing when the storage pool contains an MDisk from only one tier. 
You can disable Easy Tier or switch it to measure-only mode when creating a pool or any 
moment later. This is not possible with the GUI, only with the system CLI.
To check current Easy Tier function state on a pool, navigate to Pools → Pools, right-click the 
selected pool, choose Properties and expand View more details section, as shown in 
Figure 10-7 on page 412. 
Easy Tier can be in one of the following statuses:
/SM590000active
Indicates that a pool is being managed by Easy Tier, and extent migrations between tiers 
can be performed. Performance-based pool balancing is also enabled.
This is the expected state for a pool with two or more tiers of storage.
Note: Adjust Easy Tier load settings only if instructed to do so by IBM Technical Support or 
your solution architect.