Replacing failed RAID disks
RAID is a very useful technology, as it can help your server survive the crash of a single disk. RAID is not a backup solution, but more of a safety net that will hopefully prevent you from having to reload a server. The idea behind RAID is having redundancy, so that data is mirrored or striped among several disks. With most RAID configurations, you can survive the loss of a single disk, so if a disk fails, you can usually replace it and re-sync and be back to normal. The server itself will continue to work, even if there is a failed disk. However, losing additional disks will likely result in failure right away. When a RAID disk fails, you will need to replace that disk as quick as you can, hopefully before another disk goes too.
The default live installer for Ubuntu Server doesn't offer a RAID setup option, but the alternate installer does. If you wish to set up Ubuntu Server, check out the Appendix at the end of this book.
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