[SATLUG] First question - RAID5 quit working

David Labens adlabens at swbell.net
Mon Aug 17 00:36:48 CDT 2009


I've done apt-get to download & install smartctl.  But, the "short self-test" alludes me.  If you're talking about:

smartctl /dev/sda -i

Then it responds with:

Model Family:     Western Digital Caviar Second Generation Serial ATA family
Device Model:     WDC WD2500AAKS-00VSA0
Serial Number:    WD-WMART1760390
Firmware Version: 01.01B01
User Capacity:    250,059,350,016 bytes
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   8
ATA Standard is:  Exact ATA specification draft version not indicated
Local Time is:    Sun Aug 16 23:41:57 2009 CDT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

and it has the exact same information for sdb, sdc, & sde (sdd is the 80 gb OS drive), with the only exception being the device model & serial # (the model # is the same, but has a different extension - presumably mfg batch#).

Is that the "short self-test" to which you were referring?

David Labens

San Antonio, TX

--- On Sun, 8/16/09, Don Wright <satlug at sbcglobal.net> wrote:

From: Don Wright <satlug at sbcglobal.net>
Subject: Re: [SATLUG] First question - RAID5 quit working
To: "The San Antonio Linux User's Group Mailing List" <satlug at satlug.org>
Date: Sunday, August 16, 2009, 4:53 PM

On Sat, 15 Aug 2009 17:43:54 -0700 (PDT), David Labens
<adlabens at swbell.net> wrote:

>root at RCH-SERVER:/home/admiral# mdadm --assemble --scan
>mdadm: /dev/md/0 assembled from 2 drives - not enough to start the array.
>I KNOW that two brand new Western Digital HDDs did not go bad simultaneously, and really doubt that either of them went bad.

Actually, having parts from the same batch fail simultaneously is a
rather frequent problem in RAID. It could also be a common event like a
power glitch that damaged components on both drives and was just barely
under the threshold to kill them all.

Unlike everyone else so far, I'm going to tell you to run diagnostics on
all the drives before you destroy the data on the array by forcing it to
build. Start with smartctl from smartmontools. It should be readily
available in Ubuntu. Use the short selftest to get an idea how *all* the
drives are working - it's non-destructive and only takes a couple of

Then check the two drives that aren't getting along with mdadm using the
long test. This takes a few hours but you can do both at the same time.
If this passes you can be fairly certain the drives will function once
rebuilt into the array.

Now switch to the RAID tools and check the individual drives. I'll cover
that in the next message.  --Don

A computer is a hole in your desk you pour time into.
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