[CentOS] Infrastructure HELP!

Curt Mills hacker at fluke.com
Thu Oct 29 19:11:25 UTC 2009

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

     www.nongnu.org/duplicity (de-dupe, S3)
     www.nongnu.org/storebackup (de-dupe)
     backuppc (sourceforge) (rpm in epel)
     www.backula.org (de-dupe)

Curt Mills, WE7U                             hacker at fluke dot com
Senior Methods Engineer/SysAdmin
   "Lotto:  A tax on people who are bad at math."     -- unknown
"Windows:  Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"

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