experiences with RAID 6

[Kent Borg]

On Thu, Jun 15, 2006 at 02:37:54PM +0100, Balvinder Kataora wrote:
> I will not be using hardware RAID as I'm not comfortable with 3ware,
> promise et al combining some sort of inhouse secret metadata to mesh
> into my data.

My instinct is for software raid too.  Keeps you from being dependent
on a specialized piece of hardware that could fail or make errors.

As for those who say software raid is slower, aren't computers getting
pretty fast?  How much money does one have to spend to get how much
speed difference?  And remember, aren't some "hardware" raid products
largely a dongle for some proprietary software?


-kb


P.S.  Have fun backing up that much data.  Sure, you will have good
disk redundancy, but what do you do if a) you have a flood or
lightning strike that kills all your disks?, or b) someone deleted
something crucial and desperately wants to go back in time to when the
data was still there?  On disk (or "on array") backups can help a lot
with case "b", but case "a" requires off-site backups.

P.P.S.  Is there such a thing as a "traveling journal"?  That is, one
would maintain a second complete off-site copy of a big disk array.
The live site would make changes to the local array, but a removable
disk would record them all.  Periodically the disk would be taken to
the off-site array, and replayed onto it--now they match to that
point.  A new journal would be running back at the live-site.  
... Could this be done with LVM?  Does LVM scale that far?