=> ctrl slot=3 ld 1 modify size=max => ctrl slot=4 ld 1 modify size=?

=> ctrl slot=3 ld 2 modify size=500 forced

Migrating a logical drive

This command enables you to adjust the stripe size (data block size) or RAID level of a selected logical drive. For more information, see "Selecting a RAID method (on page 127)."

Consider the following factors before performing a migration:

•For some RAID-level migrations to be possible, you might need to add one or more drives to the array.

•For migration to a larger stripe size to be possible, the array might need to contain unused drive space. This extra space is necessary because some of the larger data stripes in the migrated array are likely to be filled inefficiently.

IMPORTANT: An array expansion, logical drive extension, or logical drive migration takes about 15 minutes per gigabyte. While this process is occurring, no other expansion, extension, or migration can occur simultaneously on the same controller. Controllers that do not support a battery-backed write cache do not support this process.

Syntax:

<target> modify [raid=01+0156adg?] [ss=8163264128256default?]

where <target> is a logical drive.

The following limitations apply to this command:

•You cannot simultaneously query the RAID level and the stripe size of any given logical drive.

•If you do not specify a RAID level for a query or migration, the CLI uses the existing value by default.

•If you do not specify a stripe size, the CLI uses the default stripe size value for the RAID level that you specify.

Example commands:

=> ctrl slot=3 ld 1 modify raid=1 => ctrl slot=4 ld 2 modify ss=16

=> ctrl slot=2 ld 3 modify raid=5 ss=16

Setting the preferred path mode

The preferred path mode determines how I/O traffic to the logical drives is managed on controllers that are in an active/active configuration.

•In Automatic mode, the storage system automatically selects a suitable path for I/O traffic to each logical drive depending on the host I/O patterns at the time. Because the optimum path can vary with time, I/O traffic for any given logical drive can be directed through either controller.

•In Manual mode, all I/O traffic to a given logical drive is directed through a designated controller. In this case, you must also specify the preferred controller for each logical drive ("Assigning a redundant controller to a logical drive" on page 75).

Syntax:

<target> modify [preferredpathmode=automaticmanual?]

where <target> is a redundant controller.

Example command:

controller ch="lab 3" modify ppm=manual

Operations 74