Dell POWERVAULT MD3620I - Manual (Page 45)

Planning: MD3600i Series Storage Array Terms and Concepts 45
The storage array 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 storage array resumes after the current cycle.
If the media verification process on a disk group is stopped due to a RAID
controller module restart, the storage array resumes the process from the last
checkpoint.
Virtual Disk Operations Limit
The maximum number of active, concurrent virtual disk processes per RAID
controller module installed in the storage array is four. This limit is applied to
the following virtual disk processes:
• Background initialization
• Foreground initialization
• Consistency check
• Rebuild
• Copy back
If a redundant RAID controller module 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 4.
Disk Group Operations
RAID Level Migration
You can migrate from one RAID level to another depending on your
requirements. For example, fault-tolerant characteristics can be added to a
stripe set (RAID 0) by converting it to a RAID 5 set. MDSM provides
information about RAID attributes to assist you in selecting the appropriate
RAID level. You can perform a RAID level migration while the system is still
running and without rebooting, which maintains data availability.
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