Dell PowerVault MD3000i - Manual (Page 37)

Using Your RAID Enclosure
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The RAID controller module tracks the cycle for each disk group independent
of other disk groups on the controller and creates a checkpoint. If the media
verification operation on a disk group is preempted or blocked by another
operation on the disk group, the firmware resumes after the current cycle. If
the media verification process on a disk group is stopped due to a RAID
controller module restart, the firmware resumes the process from the last
checkpoint.
Virtual Disk Operations Limit
The maximum number of active, concurrent virtual disk processes per
controller is four. This limit is applied to the following virtual disk processes:
background initialization, foreground initialization, consistency check,
rebuild, and copy back.
If a redundant controller fails with existing virtual disk processes, the
processes on the failed controller are transferred to the peer controller. A
transferred process is placed in a suspended state if there are four active
processes on the peer controller. The suspended processes are resumed on the
peer controller when the number of active processes falls below four.
Disk Group Operations
RAID Level Migration
Over time, you might determine that characteristics of the initial RAID level
you set initially are no longer appropriate for your enterprise. For example,
you can add fault-tolerant characteristics to a stripe set (RAID 0) by
converting it to a RAID 5 set. Select the virtual disk that you want to change
and select the type of RAID level to which you want to migrate. MD Storage
Manager provides information about RAID attributes to assist you in
selecting the appropriate level. You can perform a RAID level migration while
the system is still running and without rebooting, which maintains data
availability.
Segment Size Migration
Segment size refers to the amount of data (in kilobytes) that the RAID
controller module writes on a single physical disk in a virtual disk before
writing data on the next physical disk. Valid values for the segment size are 8,
16, 32, 64, 128, 256, and 512 KB.