RAID on RedHat 3 ES

[Michael Wimpee]

On Thu, Aug 19, 2004 at 04:02:16AM -0500, Steve Phillips wrote:
> 
> Software RAID comes with a preformance hit that with todays processors
> you probably will never notice.
> 
> RAID1 would be ok, if you are after rock solid redundancy then
> purchase another drive as a hot spare (and if your really keen, try to
> ensure that the drives are nto from teh same production batch)
> 
Be aware however, that under heavy I/O, a failed disk may take a
*really* long time to rebuild under software RAID. We saw >150MB/s using
four SCSI drives under software RAID 5, but when testing rebuild speed,
normal disk I/O caused the rebuild time to get pushed out towards
infinity. It wouldn't have worked well in our situation so we went with
a hardware RAID controller.

Mike Wimpee

> comments like "dont know if it is really effective" are kinda wishy washy, 
> effective against what ? was he saying that a single drive system would 
> have greater redundancy than a mirrored setup ? what sort of effect was he 
> commenting on ?
> 
> the preformance hit you will see will also depend on how many users and 
> how busy you expect the server to be - also, buying 5400rpm drives will 
> probably not help much, try and get reasonably fast drives with a 
> reasonable ammount of cache ram.
> 
> if you are after reliability only then there is no point to stripe 
> (infact, some people claim that software stripes actually slow things down 
> over say - RAID 10)
> 
> 
> -- 
> Steve.
> 
> On Thu, 19 Aug 2004, kenwardc wrote:
> 
> >Hi All
> >
> >Someone said to me today they didn't know whether RAID on Linux was
> >very effective. Can someone tell me whether it's still worth RAIDing
> >drives on Linux? I'm building a new mail server and I wanted to put in
> >RAID 1 just in case of problems with drives etc. down the line. Any
> >advice appreciated.
> >
> >Also, provided the answer to the question is YES, is RAID 1 the best
> >for a mail server or should I be looking at striping? I'm obviously
> >not looking for the greatest speed but want absolutely reliable
> >redundancy.
> >
> >Regards
> >Chris
> >
> >
> >
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> 
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