How to recover from a drive failure in a RAID 5 configuration?

This morning a drive failed on our database server. The drive array (3 disks) is setup in a RAID 5 configuration.

While we wait for a drive replacement we are preparing for a recovery strategy. Users are continuing to work on the system, albeit very slowly (don't know why??).

How does one install the new drive - will the data for this drive automatically be rebuilt from the parity or is there another process we should follow?

Edit: This is a hardware RAID controller. (Thanks for the answers so far, appreciated)

2 Answers

  • 5 months ago

    depending on the exact raid setup (software vs hardware and the type of hardware)

    you might have to bring the array down to rebuild (but that is for low end arrays)

    the standard rebuild process for raid 5, you just slap a new drive in (identical to the old one) and it will start rebuilding the data automatically

  • 5 months ago

    1) Backup.

    Right now no data has been lost. If your backups are not up to date backup now.

    2) Read the manual, call the vendor etc.

    Different RAID systems have different steps for replacing a disk, and done wrong you risk destroying the whole array. Without knowing what sort of RAID hardware/software you have we can only guess at the steps needed.

    Also, the slow performance is because RAID 5 in a degraded state (i.e.: one disk dead) has horrible read performance. How horrible depends on how the parity is stored and which disk died, but the "good" news is slow performance with one disk gone is a known issue and not cause for panic.

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