Dell PowerVault MD3000 - Manual (Page 98)

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Maintaining a Storage Array
where segmentSizeValue is the new segment size you want to set. Valid
segment size values are 8, 16, 32, 64, 128, 256, and 512. You can identify the
virtual disk by name or World Wide Identifier (WWID) (see "Set Virtual
Disk" on page 198).
Defragmenting a Disk Group
When you defragment a disk group, you consolidate the free capacity in the
disk group into one contiguous area. Defragmentation does not change the
way in which the data is stored on the virtual disks. As an example, consider a
disk group with five virtual disks. If you delete virtual disks 1 and 3, your disk
group is configured in the following manner:
space, virtual disk 2, space, virtual disk 4, virtual disk 5, original unused
space
When you defragment this group, the space (free capacity) is consolidated
into one contiguous location after the virtual disks. After being
defragmented, the disk group is:
virtual disk 2, virtual disk 4, virtual disk 5, consolidated unused space
To defragment a disk group, run the following command:
start diskGroup [ diskGroupNumber ] defragment
where diskGroupNumber is the identifier for the disk group.
NOTE:
Defragmenting a disk group starts a long-running operation.
Troubleshooting and Diagnostics
If a storage array exhibits abnormal operation or failures, you can use the
commands described in this section to determine the cause of the problems.
Collecting Physical Disk Data
To gather information about all the physical disks in a storage array, run the
save allPhysicalDisks command. This command collects sense data from all
the physical disks in a storage array and saves the data to a file. The sense data
consists of statistical information maintained by each of the physical disks in
the storage array.