Subject: Re: SOFTDEPS safe for qmail?
To: Don Lewis <Don.Lewis@tsc.tdk.com>
From: Robert Elz <kre@munnari.OZ.AU>
Date: 06/16/2000 21:38:43
Date: Fri, 16 Jun 2000 00:45:44 -0700
From: Don Lewis <Don.Lewis@tsc.tdk.com>
| The only problem I can think of for something like qmail is if it does
| something like:
| write message to file
| fsync file
| rename file (to indicate that the file is a complete message)
| tell sender that the message has been received
That is almost certainly what it does, it is what sendmail does.
Something like that is needed in any unix mailer - a way to ensure
that the message has been properly queued before telling the sender
that they are no longer responsible for delivery.
| This depends on rename() being synchronous
Yes. And that fsync() works.
I don't know if it is feasible with softdep or not, but a (per-process)
option that makes rename() synchronous (truly synchronous) for the
process would allow the mail spool filesys (the one where /var/spool/mqueue
or qmail's equivbalent of that lives, not /var/mail) to remain using
softdeps, and be safe.