xfs_force_shutdown after Raid crash

[Michael Monnerie]

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
-- 
// Michael Monnerie, Ing.BSc    -----      http://it-management.at
// Tel: 0660 / 415 65 31                      .network.your.ideas.
// PGP Key:         "curl -s http://zmi.at/zmi.asc | gpg --import"
// Fingerprint: AC19 F9D5 36ED CD8A EF38  500E CE14 91F7 1C12 09B4
// Keyserver: wwwkeys.eu.pgp.net                  Key-ID: 1C1209B4