content_image/989735.jpg
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. 

<img src='content_image/989735.jpg'>

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. 

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> 

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. 

