Suse on Sata

Michael L Torrie torriem at chem.byu.edu
Mon Aug 7 16:32:23 MDT 2006


On Mon, 2006-08-07 at 16:22 -0600, Andrew Jorgensen wrote:
> On 8/7/06, Stuart Jansen <sjansen at buscaluz.org> wrote:
> > On Mon, 2006-08-07 at 13:34 -0700, Hill, Greg wrote:
> > > > Unless you invest in a high-end hardware RAID solution like
> > > > LSI's MegaRAID or 3Ware, stay away from SATA RAID solutions
> > >
> > > Is this a linux-only thing or general advice?
> 
> Windows also has software RAID (at least 0 and 1 maybe others).  I
> have no idea how good or bad it might be but it probably works fine.
> I also haven't actually used it so don't ask me for advice.  You can't
> use it on your system partition though.
> 
> I prefer software RAID because it's usually easier to talk to when
> there are problems.  Mainly it's easier because you don't have to
> install someone's crappy proprietary RAID management tools that aren't
> compatible with your libc anyway and read a new set of manuals.
> Hardware RAID sometimes has more Enterprise in it though, if you like
> that.

We're in the process of looking at Sun's new Thumper storage system
(http://www.sun.com/servers/x64/x4500/ ).  This machines comes with 48
SATA disks packed in a 4U box.  But the interesting aspect of this is
that there is *no* RAID controller.  Sun doesn't even offer this.
Instead thumper uses Solaris and ZFS to carve up the 48 disks into any
size of volume you want with any level of redundancy.  I guess the Sun
buzzword is "RAID-Z."  And say what you want about Sun and their
marketing hype, but honestly ZFS looks like the way to go for software
arrays.  At runtime you can shrink and grow volumes (like LVM2) and also
change the level of redundancy.  The system will redistribute the data
stripes automatically.  So no more worrying about Raid 1, Raid 10 or
Raid 5 or Raid 5+1.  Just say 100% redundancy -- the equivalent of
RAID-10, or 33% redudancy, or what-have you.  Not sure how it will pan
out in the real world, but I think this idea has real merit.  And the
price is right (they will beat Apple's education price for storage).

So for many things I think hardware RAID is not that important.  Bear in
mind the one issue with software RAIDS (which ZFS does not suffer from)
is data losses due to how the OS's write caching works (and the drive's
cache too).  Hardware RAIDs typically have battery-backed memory that
can store pending writes if the power fails.

I plan on demoing ZFS, so I'll report on it after I do.

Michael


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