Op 2013-03-27 om 13:12 schreef Paul Mather:

> On Mar 26, 2013, at 11:44 PM, Bill Arlofski wrote:
> > On 03/26/13 22:33, Wood Peter wrote:
> >> Hi,
> >>
> >> I'm planning to use Bacula to do file level backup of about 15 Linux
> >> systems. Total backup size is about 2TB.
> >>
> >> For Bacula server I'm thinking to buy Dell PE R520 with 24TB internal
> >> storage (8x 3TB disks) and use virtual tapes.
> >
> > Hi Peter.   First, you're going to want some RAID level on that server and
> > RAID0 is not (IMHO) RAID at all.  :)
> >
> > At a minimum you're going to want to set up (for example) RAID5 in the server
> > which will give you a maximum of 7 x 3 = 21 TB since the equivalent of 1 full
> > drive is used for parity, spread across all of the drives in a RAID5 array.
> >
> > Having said that, RAID5 does not have the best write speeds, but other RAID
> > levels that will give more redundancy and better write speeds will use
> > significantly more drives and give you less total storage. You may need to
> > spend some time to consider your redundancy and read/write throughput
> > requirements.
> >
> > Also, you will generally want to configure at least one drive as a hot spare
> > so the RAID controller can automatically and immediately fail over to it in
> > the case of a drive failure in the array.
> >
> > So that takes away at least 3 more TB, so now your down to 18TB total storage
> > with a minimally configured RAID5 array with 1 hot spare.
> >
> > Just some things to consider. :)
>
>
> Another thing to consider is that with large capacity drives (3 TB)
> combined into large RAID-5 arrays there is an increased likelihood of
> a catastrophic array failure during an array rebuild due to an initial
> drive failure.  For this reason, RAID-6 would be preferred for such
> large arrays.
>
> Reliability of large RAID arrays is one of the motivations
> behind raidz3 (triple-parity redundancy) in ZFS.  See, e.g.,
> http://queue.acm.org/detail.cfm?id=1670144 for details.
>

Thanks for the advice on RAID configuration. Now we can go back to

> >> 24TB internal storage (8x 3TB disks) and use virtual tapes.

so (cheap) disks as alternative to backup tapes.


Groeten Stappers

------------------------------------------------------------------------------
Own the Future-Intel® Level Up Game Demo Contest 2013
Rise to greatness in Intel's independent game demo contest.
Compete for recognition, cash, and the chance to get your game
on Steam. $5K grand prize plus 10 genre and skill prizes.
Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d
_______________________________________________
Bacula-users mailing list
Bacula-users AT lists.sourceforge DOT net
https://lists.sourceforge.net/lists/listinfo/bacula-users