Re: Lost file-system story

[Simon Burge <simonb%NetBSD.org@localhost>]

Manuel Bouyer wrote:

> On Wed, Dec 07, 2011 at 10:59:11AM +0100, Joerg Sonnenberger wrote:
> > On Wed, Dec 07, 2011 at 10:54:40AM +0100, Manuel Bouyer wrote:
> > > On Wed, Dec 07, 2011 at 10:21:14AM +1100, Simon Burge wrote:
> > > > David Holland wrote:
> > > > 
> > > > > There is at least one known structural problem where atime/mtime
> > > > > updates do not get applied to buffers (but are instead saved up
> > > > > internally) so they don't get written out by the syncer.
> > > > > 
> > > > > We believe this is what causes those unmount-time writes, or at least
> > > > > many of them.
> > > > 
> > > > I understand the delayed atime writes were to added to reduce the number
> > > > of times a laptop harddisk spins up.  I've often wondered if a simple
> > > > sysctl could be added to control this.
> > > > 
> > > > Unmounting my /home on my main machine takes approximately a minute.  My
> > > 
> > > 
> > > Seconded. On a ftp server with a large filesystem (5TB, 5M inodes), 
> > > shutdown
> > > takes a very long time too.
> > 
> > Isn't that more the issue of writing out the atime updates?
> 
> Yes, that's it. Wasn't Simon talking about this ?

Yes.  We all appear to be in total agreement here :)

Cheers,
Simon.