To determine which tier is assigned to an MDisk, click  Pools  External Storage . Then, click  Actions  Customize columns  and select  Tier . This includes the current tier setting into a  list of MDisk parameters that are shown in the  External Storage  pane. You can also find this  information in MDisk properties. To show this information, right-click MDisk, select  Properties , and expand “View more details” section, as shown in Figure 9-6. To list MDisk parameters with the CLI, use the  lsmdisk  command. The current tier for each  MDisk is shown. To change the external MDisk tier, use  chmdisk  with the  -tier  parameter as  shown in Example 9-1. For an external MDisk, the system cannot calculate its exact performance capabilities, so it  has a number of predefined levels. In rare cases, statistics analysis might show that Easy Tier  is overusing or under-utilizing an MDisk. If so, levels can be adjusted, which can be done 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 Figure 9-2 on  page 444.  Note:  Adjust Easy Tier load settings only if instructed to do so by IBM Technical Support or  your solution architect. Chapter 9. Advanced features for storage efficiency  443 Figure 9-6 MDisk properties Example 9-1 Listing and changing tiers for MDisks (partially shown) IBM_Storwize:ITSOV5K: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:ITSOV5K:superuser>chmdisk -tier tier1_flash mdisk2 IBM_Storwize:ITSOV5K:superuser>