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Re: xfs_force_shutdown after Raid crash

To: xfs@xxxxxxxxxxx
Subject: Re: xfs_force_shutdown after Raid crash
From: Michael Monnerie <michael.monnerie@xxxxxxxxxxxxxxxxxxx>
Date: Wed, 4 Feb 2009 09:52:45 +0100
In-reply-to: <20090203154907.GA21278@xxxxxxxxxxxxx>
Organization: it-management http://it-management.at
References: <498376CF.8020806@xxxxxxxxxxxxxx> <200902031140.08576@xxxxxx> <20090203154907.GA21278@xxxxxxxxxxxxx>
User-agent: KMail/1.10.3 (Linux/2.6.27.13-ZMI; KDE/4.1.3; x86_64; ; )
On Dienstag 03 Februar 2009 Christoph Hellwig wrote:
> Yeah, that sounds correct.  Do you volunteer for the FAQ entry?
>  xfs.org is a wiki so you could add it.  I'm happy to proof-read it
> if you want.

I don't know if it's good and correct, I just put this in the wiki, and 
additionally changed 2 sections, please check the wiki log if it's 
correct:

== Q. What about the hard disk write cache? ==

The problem with hard disk write caches is that their contents are lost 
in case of a power outage. With hard disk cache sizes of currently up to 
32MB that can be a lot of valuable information.

With a single hard disk and barriers turned on (on=default), a powerfail 
"only" looses data in the cache but at least does not destroy the 
filesystem.

With a RAID controller with battery backed cache, you should turn off 
barriers, as recommended above. But then you *must* disable the hard 
disk write cache in order to ensure to keep the filesystem intact after 
a power failure.

mfg zmi
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