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Re: ext3 and chattr +S on postfix spools



Maybe there is an opening for "mtafs" :) which would have the semantics
which the MTA authors want and reasonable features which are useful to
others [journalling,speed,io-clustering,etc]

The question is what precise semantics of ffs does ext3 and
ffs/softupdate not provide which makes running a MTA on any recent OS 
similar to playing russian roulette with mail

BTW, It seems that ext3-users redhat com is a subscription only list,
maybe sct might be able to convice the RH IS staff to use TMDA
<http://tmda.sf.net/> for non-subscribers

> ext3 is unsafe for maildir, and with softupdates, so is ffs.
> One step forwards, two steps back.
> 
> Fortunately, some people still have a choice.
> 
> 	Wietse
> 
> adi:
> > On Mon, Feb 04, 2002 at 10:34:02PM +0000, Stephen C. Tweedie wrote:
> > > On Mon, Feb 04, 2002 at 05:34:52PM +0800, Yusuf Goolamabbas wrote:
> > > > Postfix <http://www.postfix.org> does a chattr +S on its spool directory
> > > > when it is installed on Linux.
> > > > 
> > > > Is this still required on ext3 ?
> > > 
> > > I'm not sure --- it depends on what Postfix's assumptions are.  If it
> > > expects all directory operations to be synchronous then the flag is
> > > still needed.  If it is satisfied with fsync flushing dir information,
> > > then no it is not needed.
> > 
> > I don't say that I know postfix better. Beside for calling fsync()
> > to ensure that message safely stored on the disk, postfix also
> > use rename(2) to move message accross queue dirs. It's okay because
> > postfix's queue-id use inode as it's name.
> > 
> > If I understand correctly, link(2) and unlink(2) implementation
> > on ext3fs will be done asynchronously. This is use by postfix
> > (unlink()) to remove messages that already delivered (by calling
> > remove()).
> > 
> > So, in case of power outage for example, no message will get lost,
> > but possibly be delivered twice. Note that postfix also mark all
> > of recipients which are already delivered as done (but without calling
> > fsync()).
> > 
> > Then *I think* it's save to get rid chattr +S on ext3fs.
> > 
> > On other issue, postfix also support local delivery using maildir
> > format (http://cr.yp.to/proto/maildir.html) which is use link(2)
> > and unlink(2). If there is power outage, it is possible that
> > linking file from tmp to new get failed. This is the same with
> > losing message as there is no MUA or other mail retreival agent
> > use that files which still stay on tmp directory.
> > 
> > Regards,
> > 
> > P.Y. Adi Prasaja
> > 
> > -
> > To unsubscribe, send mail to majordomo postfix org with content
> > (not subject): unsubscribe postfix-users
> > 
> > 
> 
> -
> To unsubscribe, send mail to majordomo postfix org with content
> (not subject): unsubscribe postfix-users
> 

-- 
Yusuf Goolamabbas
yusufg outblaze com





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