Re: devices get kicked from RAID about once a month

["Stefan /*St0fF*/ Hübner" <st0ff@gmx.net>]

-------- Original-Nachricht --------
Betreff: Re: devices get kicked from RAID about once a month
Datum: Wed, 02 Jun 2010 19:08:58 +0200
Von: Stefan /*St0fF*/ Hübner <st0ff@gmx.net>
Antwort an: st0ff@npl.de
An: Dan Christensen <jdc@uwo.ca>

Am 02.06.2010 18:33, schrieb Dan Christensen:
> John Robinson <john.robinson@anonymous.org.uk> writes:
> 
>> My Samsung Spinpoint F1's can have TLER enabled using a more recent
>> smartctl. It's not appeared as part of a formal release yet but a
>> patch went in to r3065 in SVN:
>> http://sourceforge.net/apps/trac/smartmontools/log/trunk/smartmontools
> 
> Thanks.  I got the svn3077 from Debian testing, but it doesn't seem to
> be supported with my drives:
> 
> # smartctl -l scterc /dev/sda
> smartctl 5.40 2010-03-16 r3077 [i686-pc-linux-gnu] (local build)
> Copyright (C) 2002-10 by Bruce Allen,
> http://smartmontools.sourceforge.net
> 
> Warning: device does not support SCT Commands

There you have it: the drives are not supporting SCT-ERC.  Which I can
say is true: I also own an SP2504C.
> 
> Any other suggestions?

Not really, it's up to Neil to export some sysfs-variable, where you
could tune how long a drive may take to respond to some command.

The "trying hard to get the data back" can take up to a few minutes
(somewhere I read about 2, somewhere else about 3 minutes).  And what
really is happening is: after some timeout the mdraid "thinks
correctly", that the drive cannot provide the requested sector.  To
prevent failure, it reconstructs the "missing" data and issues a write
request.  Unfortunately the drive still tries to reconstruct the data
itself and will not respond.  After those write requests failing, mdraid
drops the disk.

The ERC-setting is volatile.  You'd have to issue it on every reboot,
and on every hotswap.  But at first you'd have to get drives that
support this setting.

stefan
> 
> Dan
> 
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