Re: stagger forced fsck on reboot

[Drew Parsons <dparsons@debian.org>]

On Tue, 2006-06-27 at 09:04 +0200, Wouter Verhelst wrote:
> On Tue, Jun 27, 2006 at 11:39:22AM +1000, Drew Parsons wrote:
> > On Fri, 2006-06-23 at 17:18 +0200, Wouter Verhelst wrote:
> > > I fail to see why this
> > > would be a problem or is, indeed, relevant.
> > 
> > I'm sorry, Wouter, it's not clear to me that you correctly read the
> > problem I was describing.
> 
> Well, I did. What you meant is that staggering the counter is only going
> to work until the first forced fsck done on all filesystems, since at
> that time, they're all back in sync again.
> 
> However, what I'm saying is that such an event is extremely rare on
> ext3, since a journal replay can, IME, deal with most filesystem
> inconsistencies. The chance of a forced fsck occurring on ext3 due to
> inconsistencies, and a resulting synchronisation of the staggered mount
> count is therefore negligable.
> 

OK, I see what you mean now.  You're saying that the possibility of
subverting the staggered count isn't an extremely serious problem since
it's isn't all that likely to occur, not automatically anyway.  However
I'm not sure it's negligable.

For instance a laptop owner may have had such a bad crash that s/he
wants to manually force a full fsck on all partitions, and let the
system continue with running its own checks automatically after that as
normal.  But doing this will synchronise the counts, bringing that
system back to the inconvenient scenario which we've been discussing.
Of course h/she could manually reset the counts at the same time as
manually running the full fscks, but the whole point here is too make
things just a little simpler for them so they don't have to make extra
manual adjustments like that.

Of course once someone presents an actual patch to implement all this,
it should be simple enough to switch between either of the two methods,
staggering the max count or staggering the initial count :)   

Nevertheless I think I'd be more comfortable staggering the max mount
parameter rather than the accumulated mount count. :)

Drew