auto-rebuild RAID mirrors

Tom Buskey tom at buskey.name
Thu Apr 19 13:09:19 EDT 2007


On 4/19/07, Bill McGonigle <bill at bfccomputing.com> wrote:
>
> On Apr 18, 2007, at 10:35, Thomas Charron wrote:
>
> >   You're right, I'm
> > suprised there isn't more on this online.  It's a GREAT idea to mirror
> > a local drive over an external mass storage drive.
>
> It's worth noting that I only usually achieve about a real 14MB/s on
> the USB drives.  Firewire gets about 24MB/s, but I had to pull that
> card when I got a new mobo to fit an e.SATA card in (fewer slots).


I'm getting about 20 MB/s writes over gigabit ethernet to an NFS/Samba
server.

1 system is a Compaq 1850r dual PIII 500MHz 512MB w/ a $20 4 port SATA I
card and 3 120GB drives in RAID 5 on a Fedora 5 system.  Local disk is about
21 MB/s.  Lowend stuff.

The other system is an AMD Dual Core (165?) 1GB RAM with builtin SATA II.  I
have 4 500GB Seagates running Solaris 10 with ZFS RAID-Z.  Local disk is 60
MB/s uncompressed.  I did a dd if=/dev/zero onto a compressed ZFS area and
got 173 MB/s with 30% compression.  Gigabit ethernet is around 20 MB/s.

I have not done any tuning, but this beats your USB drives and isn't far
from Firewire over ethernet.  Local disk on the Solaris system really beats
it.

It's also worth noting that ZFS does all of this automatically
> already, including the snapshots (instantly), so I'll probably try
> moving the whole backup system to ZFS when I get another machine for
> a Nexenta (Ubuntu on an OpenSolaris kernel) box.


ZFS is very cool as I've said before.  You have to tell it to snapshot or
clone, but there are scripts that can automate it.  I think it could be
comparable to NetApp's multiple simultaneous snapshotting.

The big hit with Solaris is support for the SATA card.  Not many are
confirmed.  It doesn't like RAID in the BIOS, but the cards need BIOS.  My
$20 card didn't work but others have been able to reflash.  I bricked mine.

I ended up copying someone's recipe for my server.  Including data disks was
under $2k from Newegg.

If you want a very solid production server, go with Solaris 10u3.  The
desktop isn't as complete as Linux but that doesn't matter so much on a
server.  If you want experimental, OpenSolaris based might work better as a
desktop.  If you want iSCSI target, that's in OpenSolaris.  Solaris 10 u4
should have it when it comes out in June.
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