DELL MD3220 사용자 설명서

Planning: MD3200 Series Storage Array Terms and Concepts

A consistency check verifies the correctness of data in a redundant array 

(RAID levels 1, 5, 6, and 10). For example, in a system with parity, checking 

consistency involves computing the data on one physical disk and comparing 

the results to the contents of the parity physical disk.
A consistency check is similar to a background initialization. The difference is 

that background initialization cannot be started or stopped manually, while 

consistency check can.

It is recommended that you run data consistency checks on a redundant 

array at least once a month. This allows detection and automatic replacement of 

unreadable sectors. Finding an unreadable sector during a rebuild of a failed 

physical disk is a serious problem, because the system does not have the 

redundancy to recover the data.

Another background task performed by the storage array is media verification 

of all configured physical disks in a disk group. The storage array uses the 

Read operation to perform verification on the space configured in virtual 

disks and the space reserved for the metadata.

The media verification operation runs only on selected disk groups, 

independent of other disk groups. Cycle time is the time taken to complete 

verification of the metadata region of the disk group and all virtual disks in 

the disk group for which media verification is configured. The next cycle for a 

disk group starts automatically when the current cycle completes. You can set 

the cycle time for a media verification operation between 1 and 30 days. The 

storage controller throttles the media verification I/O accesses to disks based 

on the cycle time. 
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.

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