jorgnsn@qucis.UUCP (John Jorgensen) (11/03/88)
We just bought an Exabyte 8200 8mm drive to do backups for our network of Suns, and I'm trying to figure out when we can run our full dumps, now that we don't need someone around to change tapes. The man entry for dump says that you should bring the system down to single-user mode to do level 0 dumps. Until now, we have been doing full backups to 1/2" tape by halting all the client machines, dumping the first few filesystems with only the file servers running, then bringing the system up with the last filesystem's mode changed to allow root access only, and dumping that filesystem while the others are available to users. We have been running nightly incremental dumps at 1 a.m. with the system fully available (we do have a handful of users who log on at such hours). I have not seen restore fail on any of the nightly tapes. Now that we have the Exabyte, we would like to do unattended full backups at night, so that we don't have to bring the system down every week. I think that the system is pretty quiet between 0200 and 0600, but I don't see any way to prohibit access then. If I do full dumps while there is a user or two active, how big is the risk that the dump won't work correctly? Am I only risking messing up the files that the user happens to be using at the time, or could the entire dump be compromised? If it's just a matter of missing the occasional file, I think I'd be willing to trade that off on the increased redundancy we would get from running full dumps more often. I'm especially interested in hearing how people who already have Exabytes or similar drives are handling unattended full dumps. Has anyone thought of a method for making a filesystem inaccessible during the dump (if you just change permissions, what happens to the person who started editting a file in the filesystem just before you took away his ability to write to it?). You can send replies to me, or post to the net--this issue might actually prompt some discussion, though it's hard to imagine much controversy arising from the mundane question of running backups. John Jorgensen jorgnsn@qucis.bitnet jorgnsn@qucis.queensu.ca