[176713] in North American Network Operators' Group
Re: Got a call at 4am - RAID Gurus Please Read
daemon@ATHENA.MIT.EDU (Javier J)
Wed Dec 10 17:18:57 2014
X-Original-To: nanog@nanog.org
In-Reply-To: <86mw6vpqre.fsf@valhalla.seastrom.com>
Date: Wed, 10 Dec 2014 17:18:49 -0500
From: Javier J <javier@advancedmachines.us>
To: Rob Seastrom <rs@seastrom.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
I'm just going to chime in here since I recently had to deal with bit-rot
affecting a 6TB linux raid5 setup using mdadm (6x 1TB disks)
We couldn't rebuild because of 5 URE sectors on one of the other disks in
the array after a power / ups issue rebooted our storage box.
We are now using ZFS RAIDZ and the question I ask myself is, why wasn't I
using ZFS years ago?
+1 for ZFS and RAIDZ
On Wed, Dec 10, 2014 at 8:40 AM, Rob Seastrom <rs@seastrom.com> wrote:
>
> The subject is drifting a bit but I'm going with the flow here:
>
> Seth Mos <seth.mos@dds.nl> writes:
>
> > Raid10 is the only valid raid format these days. With the disks as big
> > as they get these days it's possible for silent corruption.
>
> How do you detect it? A man with two watches is never sure what time it
> is.
>
> Unless you have a filesystem that detects and corrects silent
> corruption, you're still hosed, you just don't know it yet. RAID10
> between the disks in and of itself doesn't help.
>
> > And with 4TB+ disks that is a real thing. Raid 6 is ok, if you accept
> > rebuilds that take a week, literally. Although the rebuild rate on our
> > 11 disk raid 6 SSD array (2TB) is less then a day.
>
> I did a rebuild on a RAIDZ2 vdev recently (made out of 4tb WD reds).
> It took nowhere near a day let alone a week. Theoretically takes 8-11
> hours if the vdev is completely full, proportionately less if it's
> not, and I was at about 2/3 in use.
>
> -r
>
>
