HP Configuring Arrays Reference Manual page 72

If the operating system does not support logical drive extension, carrying out this command makes data on
the logical drive unavailable. Therefore, the CLI displays a warning prompt as a safeguard in case you are
using such an operating system. To prevent the prompt from appearing, use the forced parameter.
Example commands:
=> 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 121)."
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:
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=0|1+0|1|5|6|adg|?] [ss=8|16|32|64|128|256|default|?]
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
controller to a logical
Syntax:
An array expansion, logical drive extension, or logical drive migration takes
drive" on page 73).
("Assigning a redundant
HP Array Configuration Utility 72