[176709] in North American Network Operators' Group
Re: Got a call at 4am - RAID Gurus Please Read
daemon@ATHENA.MIT.EDU (Rob Seastrom)
Wed Dec 10 08:40:31 2014
X-Original-To: nanog@nanog.org
To: Seth Mos <seth.mos@dds.nl>
From: Rob Seastrom <rs@seastrom.com>
Date: Wed, 10 Dec 2014 08:40:21 -0500
In-Reply-To: <54880935.7040103@dds.nl> (Seth Mos's message of "Wed,
10 Dec 2014 09:49:57 +0100")
Cc: nanog@nanog.org
Errors-To: nanog-bounces@nanog.org
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
