Why idle backups?? (was Re: Looking for shell script for backup on BSD 4.3)

[Elizabeth Zwicky]

In article <1990Oct29.225451.29481 at usenet.ins.cwru.edu> edguer at charlie.CES.CWRU.Edu (Aydin Edguer) writes:
>I would like to suggest that going to single-user for a level 0 backup is
>unnecessary.  All that really needs to be done is to unmount the (4.2/ufs)
>file system.  This means that the computer can continue to function and
>even serve diskless clients (as long as you are not backing up /export).
>This permits the whole thing to be done in a script from "cron" or "at" without
>mucking with your rc files.  The only file system that may not be backed
>up in this manner is the root partition.  /usr is normally (SunOS4.1) read-only
>and thus does not need to be backed up.

You can't unmount an active file system except by rebooting the
machine - so if you need to guarantee the unmount will succeed, you're
back to rebooting, and fiddling with your rc files. (This should
no longer be true in BSD 4.4 release, but that's not going to do you
much good.)

/usr is read only for *clients*, not usually on the server itself. You
don't have to level 0 it if you never change it, and you don't mind
doing an OS re-install if you lose the disk. I don't like OS
re-installs, and I do install OS patches. I back up everything - if
all my disks melt down I'm going to have enough to worry about without
trying to recall exactly how to reinstall and recustomize my OS.
Actually, I don't back up swap partitions, because most of servers
have a gig devoted to client swap, and that's an awful lot of tape
when I don't actually care about the data; since all the swaps are
identical anyway, reconstructing them is no big deal for me. If we
were running a whole lot of different sizes, it might be worth the
tape even for that.

	Elizabeth Zwicky