Subject: Re: wd, disk write cache, sync cache, and softdep.
To: Bill Studenmund <wrstuden@netbsd.org>
From: Jason Thorpe <thorpej@shagadelic.org>
List: tech-kern
Date: 12/16/2004 14:00:30
--Apple-Mail-11-373179427
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset=US-ASCII; format=flowed
On Dec 16, 2004, at 12:06 PM, Bill Studenmund wrote:
> Metadata updates.
>
> If the upper level really cares about ordering, it should set this
> flag.
Well, no.
It's more complicated than that.
Ordering is only part of the issue. It's "data that is written to the
drive really bloody well is written to stable storage". This is of the
utmost importance in the presence of, say, a journaling file system ...
the file system may not be recoverable if the journal becomes corrupted
due to power failure at the drive wiping out data that hasn't landed on
the platters yet.
-- Jason R. Thorpe <thorpej@shagadelic.org>
--Apple-Mail-11-373179427
content-type: application/pgp-signature; x-mac-type=70674453;
name=PGP.sig
content-description: This is a digitally signed message part
content-disposition: inline; filename=PGP.sig
content-transfer-encoding: 7bit
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.3 (Darwin)
iD8DBQFBwgV/OpVKkaBm8XkRAjwSAJ9FLlaeRiNHSpzmYrmZbXWcoA8vJQCeJYhr
NXPfe6W3WBmjFAXpmXTT1KE=
=tDr8
-----END PGP SIGNATURE-----
--Apple-Mail-11-373179427--