On Thu, 29 Oct 2009, ML wrote:
My question is about initial setup. The 4 x 1TB drives. How to set this up for I have some protection?
RAID 0+1? (striped + mirrored) I would end up with 2TB useable space.
RAID 5? so what one is a hot spare? 3TB useable space?
What about striping the 4 1TB and mirroring that to a 4 x 1tb External drive enclosure?
Plan for drives going out but keeping the site operational. Also remember that RAID isn't a backup.
RAID 5 is enticing because you get more usable space out of your drives, but you have to be sure you'll only lose one drive at a time and can get a replacement drive in there and sync'ed up before you lose a 2nd one... If the drives were made by the same manufacturer and were bought at about the same time you might easily lose 2 or more, blowing up your array.
Go with RAID 1+0 (mirroring + striping) and you can potentially lose up to 1/2 of your drives and keep running. That's assuming you lose the correct 1/2... If you lose two drives in the same mirror you still go down.
Combine the above with a good backup strategy. Backup software has been discussed on this list quite recently so look back a few days or weeks and you'll find some good links. Practice and document doing restores so that you know how to do them quickly without error when the pressure's on.
Some of the backup software names/links I gleaned from this list recently:
www.mondorescue.org www.nongnu.org/duplicity (de-dupe, S3) www.nongnu.org/storebackup (de-dupe) amanda backuppc (sourceforge) (rpm in epel) www.backula.org (de-dupe)