On Tue, Jul 18, 2000 at 01:25:36PM -0400, Michael T. Babcock wrote:
> Is UTIME necessary in a mail queue? If a logging filesystem were mounted on a
> separate disk (or network array, etc.) specifically for the mail queue,
> shouldn't it be mounted without UTIME?
Do you mean atime or mtime? In either case, not all Unixen allow such
mount options. Sepcifically Solaris only has noatime. I'd be surprised
though if the OS wants to update the directory once a second to get
an atime/mtime on disk for an opened file. Maybe once a minute which
is not an unreasonable cost for zeroseek.
This is probably something that's more appropriately discussed on
the zeroseek list. The bottom line though is that when qmail-queue
exits(0), the email must be phsyically on disk which means there
must be at least one fsync() - no choice whatsoever.
The zeroseek question is all about how you minimize the number
of fsyncs and how you structure the queue so that the fsync() incurs
a minimal seek on disk. Oh and combine that with appropriate security
access to that queue structure and your done!
Regards.
>
> Bruce Guenter wrote:
>
> > The only way to get truely zero seek performance is to use a
> > log-structured file system on a clean disk. Otherwise, you will seek
> > occasionally to write out some dirty metadata. Even if you pre-allocate
> > your log file on a regular filesystem, you will seek occasionally (once
> > a second, AFAICT) to update the utime in the inode.
>
