Subject: Re: parity check with root on raid
To: None <netbsd-help@netbsd.org>
From: Manuel Bouyer <bouyer@antioche.eu.org>
List: netbsd-help
Date: 04/22/2005 21:45:21
On Thu, Apr 21, 2005 at 10:35:14PM +0200, Jukka Salmi wrote:
> Greg Oster --> netbsd-help (2005-04-21 08:55:31 -0600):
> [...]
> > > > Shouldn't parity be checked (and possibly be rewritten) before filesystems
> > > > are checked and mounted?
> > 
> > In theory, yes, but if you have a huge array that might take hours to 
> > check, you probably don't want the unavailable for that long.  The 
> > time it takes to do the check is the time your data is "unprotected" 
> > against a component failure, so whether you want to be "live" during 
> > is the question... 
> 
> I see. So what about a user-settable variable which determines whether
> to run 'raidctl -P' in the background and thus to continue booting, or to
> run it in the foreground and thus to wait until it returns?

If parity is to be rebuilt early in the boot process, and the boot waits for
it to be done, then there should probably be a way to disable (or at last,
agressively tune) the rate limit in the parity rebuilt thread. There's no
point trying to be gentle with other processes if the system isn't doing
anything else.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--