chmdisk

Use the chmdisk command to modify the name or IBM® Easy Tier® settings for a managed disk (MDisk).

Syntax

Read syntax diagramSkip visual syntax diagram chmdisk -namenew_name_arg-tiertier0_flashtier1_flashtier_enterprisetier_nearlinetier_scm-easytierloaddefaultlowmediumhighvery_highmdisk_idmdisk_name

Parameters

-name new_name_arg
(Optional) Specifies the new name to be applied to the managed disk.
-tier tier0_flash | tier1_flash | tier_enterprise | tier_nearline | tier_scm
(Optional) Specifies the new tier of the MDisk. The values are:
tier0_flash
Specifies a tier0_flash hard disk drive or an external MDisk for the newly discovered or external volume.
tier1_flash
Specifies an tier1_flash (or flash drive) hard disk drive or an external MDisk for the newly discovered or external volume.
tier_enterprise
Specifies a tier_enterprise hard disk drive or an external MDisk for the newly discovered or external volume.
tier_nearline
Specifies a tier_nearline hard disk drive or an external MDisk for the newly discovered or external volume.
tier_scm
Specifies a tier_scm hard disk drive or an external MDisk for the newly discovered or external volume.
Note: Since Release 8.1.0, the tier of MDisks mapped from certain types of IBM System Storage Enterprise Flash is fixed to tier0_flash, and cannot be changed.
-easytierload default | low | medium | high | very_high
(Optional) Specifies the Easy Tier load (amount) to place on a non-array MDisk within its tier.
If Easy Tier is either overusing or under-utilizing a particular MDisk, modify the easy_tier_load value to change the load size.
Note: Specifying default returns the performance capability to the value used by the system. Specify very_high only if the MDisk tier is ssd.
mdisk_id | mdisk_name
(Required) Specifies the ID or name of the managed disk to modify.

Description

This command modifies the attributes of a managed disk.

If you are upgrading your system and the back end of the system uses encrypted storage, you must indicate which MDisks are self-encrypting before you add MDisks to a storage pool. If those MDisks are part of a storage pool, the system assumes that the back-end is not self-encrypting (even if it might be).

If you create encrypted storage pools, the system encrypts locally before it sends data to the back-end. So, the back-end of the system could encrypt again and cannot compress data because the data is random and not compressible.
Note: You must upgrade the system first.
To use encryption on the system that already has encryption that is enabled on the back-end, upgrade the back-end of the system before you enable encryption on the system.

An invocation example

chmdisk -tier tier0_flash mdisk13

The resulting output:

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