Virtual disk operations limit, Disk group operations, Raid level migration – Dell POWERVAULT MD3620I User Manual

Page 45

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Planning: MD3600i Series Storage Array Terms and Concepts

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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.

book.book Page 45 Tuesday, June 18, 2013 3:09 PM

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