When a hard drive fails in a RAID array and needs to be replaced, you only have one chance to correctly identify which drive has failed and remove it. If you make a mistake and remove a drive that is considered good, the RAID array will fail and all data will be lost.
Before replacing the hard drive, make sure you have a good full, bear-metal backup of everything on that RAID array.
Ways to determine which drive has failed:
For methods 1 and 2, you can swap the hard drive with a new hard drive while the server is powered on. For method 3, you will need to power-off the server before locating / verifying which hard drive has failed and replacing it with a new drive. If you do not power-off the server (even if you are only in the RAID firmware) the RAID array will be marked as failed and all data might be lost.
Hard drive replacements should be done near the end of the business day as server performance will be greatly effected while the RAID array rebuilds.
Article ID: 197
Created: Tue, Jul 14, 2015
Last Updated: Sun, Sep 15, 2019
Author: Natural Networks NOC
Online URL: http://kb.naturalnetworks.com/article/how-to-replace-a-failed-hard-drive-in-a-raid-array-197.html