[rescue] RAID (was Re: Insane drives)

[Joshua D. Boyd]

On Tue, 10 Jul 2001, Robert Novak wrote:

> If you have 10 9.1GB disks in your set, you get 75.6GB or so (assuming no
> spares). Might want to use a hotspare if you have the capacity (Sun's
> Disksuite will let you create a hotspare pool, so put one disk in it and
> attach it to your RAID 5 metadevice).

So, you are saying that you always only use one disk for parity?  I
thought that was what raid 3 did.
 
> Note that software RAID 5 sucks. I think this has been hashed out here and
> elsewhere several times in the past, but it bears saying again. I just do
> RAID 0+1 when I'm using Disksuite--takes more disks (2x your needed space)
> but is faster in software. If you can get a hardware RAID controller for
> FC, you'd be in good shape (but probably somewhat poorer than when you
> started).

Yeah, we've pretty much established that software raid 5 isn't the best
idea unless the CPU really has nothing else to do and is pretty fast.

I don't know.  I recently went from an 8gig to a 30 gig ide drive in my
file server.  I can't place my finger on it, but since then, something has
just felt off ever since.  I had determined that I wasn't going to replace
the file server after all this year, but I don't know now.  

I certainly can't afford 30 gigs of raid5 scsi storage.  But, lots of 2
and 4 gig scsi drives are starting to be fairly cheap.  Maybe cheap enough
to consider converting my Sun 511 to whole two chains of SCSI drives and
then get a machine with two scsi controllers in it to drive them.  That
way, I might be able ot reasonably afford 10gigs (10 2gig drives, raid
1+0) of really safe storage, and then can just leave the unimportant stuff
(like build space and MP3s) on the non confidence inspiring lintel/ide
machine.  And if I did this by putting an extra scsi card in an older Sun
running Solaris 2.51, then this new file server could also be on my FDDI
concentrator acting as the gateway between the FDDI and ethernet.

I don't know.  I really shouldn't spend the money, but I always feel more
relaxed when I know that my data is safe.  Maybe I'll just try to install
my new tape drive tonight.  That might help enough.

--
Joshua Boyd