If you're like me, you have a heckuva lot more data to back up than a
single tape can contain.  You also probably have enough different
architectures around that multiple operating system-specific dump
formats are unattractive to you, even if you could dump entire
filesystems and fit them on a tape.  So what do you do?  You use GNU
tar, like everybody else.  And why does this disappoint you?  Because
it's almost 2005 and you're still clobbering atime with every nightly
backup.  How lame.  How terribly, terribly lame.  Three and a half
decades of unix and we still haven't got that fixed?

Not anymore.  Maybe.  Eventually.  At least in open source unixes.

The Linux 2.6.8 kernel introduced an O_NOATIME option to the open(2)
syscall which, when requested, will mean that subsequent read(2)s to the
fd will not alter the atime of the file.  O_NOATIME is only granted to
the user who owns the file and the superuser.

What remains to make GNU tar backups that don't clobber atime a reality?

 * A GNU tar patchset that teaches --atime-preserve about O_NOATIME and
 uses it opportunistically over the utime(2) method.
 * Probably a backport of O_NOATIME to Linux 2.4 for the [ likely
 millions of ] systems not ready to move to 2.6.
 * Kernel patchsets for your favorite BSD.

This annoys me enough that I'm willing to work on the above list.
However, my project list is such right now that it is likely several
months before I will be far enough down the list to concentrate effort
on improving our backup infrastructure and can justify spending work
hours hacking at this.  I happen to know there are tons of amanda users
on this list whose sole business and livelihood is backups.  This
message is intended to let you know that this is quite possible to
achieve today, and if backups are your business, it might be worth
something to you to spend your time improving these tools.  In other
words, if you care about this as much as I do and can work on this
sooner than I can, the work is out there waiting to be done and I'd love
to see someone jump on it.  I also know there are amanda developers out
there who already have relationships with projects like GNU tar and
might be able to exert some influence to see these features committed
and released.

Backups don't have to suck.

Brandon
-- 
Pseudo-Random Googlism:  winter is typically known for hibernation
                         periods