henry (07/19/82)
I have made some changes in the backup scheme (actually, "am making" is more accurate, the software isn't fixed up completely yet). The Sunday backups run four hours these days, which is a pain both to the hack who has to sit around watching tapes spin and to the users who'd like to work Sunday nights. Some shortening seems desirable, and I've managed to figure out what looks like a reasonable scheme. There still need to be real full backups roughly once a month, for two reasons: - a full not-too-old offsite backup is necessary - the policy of keeping full monthly backups of user files has turned out to be very helpful for file retrieval However, there is no clear-cut requirement for doing full backups on any shorter schedule. It happens that the V7 backup programs can cope with multiple levels of incremental backup, e.g. an intermediate weekly incremental between monthly fulls and daily partials. So what I'm setting up is like this: 1. Every four weeks, the Sunday backup will indeed run its full dreary length. (I may be able to speed it up some, but I'm not making promises yet.) This will be a weekly plus a monthly. 2. The rest of the time, the Sunday backup will be just a daily and a weekly. This should take under an hour. 3. The dailies will remain unchanged. The only real adverse consequences of this scheme are: A. Restoring a trashed filesystem uses more tapes, making it a more complex operation and increasing its vulnerability to bad tapes slightly. We do this once in a blue moon, and it's a long and dreary operation anyway. B. The offsite backups are not as recent (i.e. up to a month old rather than 1-2 weeks). If the building burns to the ground, I suspect an extra couple of weeks of lost work will be the least of everyone's worries. C. The length of the Sunday backups is much more variable. I'll probably set up an automatic warning message in motd for the weeks when things will run the full length. Comments and criticisms are solicited.