Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!lll-crg!nike!ucbcad!ucbvax!HI-MULTICS.ARPA!MHJohnson From: MHJohnson@HI-MULTICS.ARPA (Mark Johnson) Newsgroups: mod.computers.vax Subject: Comments about volume sets Message-ID: <860910233819.577407@HI-MULTICS.ARPA> Date: Wed, 10-Sep-86 19:38:00 EDT Article-I.D.: HI-MULTI.860910233819.577407 Posted: Wed Sep 10 19:38:00 1986 Date-Received: Fri, 12-Sep-86 20:01:22 EDT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The ARPA Internet Lines: 42 Approved: info-vax@sri-kl.arpa I have been running our 785 system w/ a three disk volume set for quite a while. Over the Labor Day holiday, one of the disks died and the data was not recoverable. In the aftermath of this failure we noted the following things that other users of volume sets might be interested in: (1) Do NOT use MOUNT/BIND to add the newly initalized disk back into the volume set. We did this and had a four disk volume set (missing drive 3) with only three disk drives. We went through great gyrations using the console floppy to make a volume 3 on disk & volume 4 on floppy so we could mount all the volumes of the volume set. (2) You cannot remove a disk from a volume set once you have added it. (3) You cannot use BACKUP/IMAGE to restore a volume set made on a four disk volume set onto a three disk volume set. (4) You cannot run ANALYZE/DISK unless all disks of the volume set are mounted at the same time. (5) There is a limit to the size of a directory file (1024 blocks or so). We filled up [SYSLOST] when we ran ANALYZE/DISK on the volume set described in (1). We had to rename [SYSLOST] & make a new one & do ANALYZE/DISK again. (6) Large directories (the 1024 block size ones) are VERY slow to add or delete files from. It took over 8 hours to delete the 22k files from our filled up [SYSLOST] directory. Overall, I recommend the regular use of IMAGE backups of volume sets along with a daily (or more frequent) incremental backups. It is far faster to recover from backup tapes than to try to extract the files on the remaining disks of the volume set. It took us almost 36 hours to recover our volume set the hard way. I estimate it would take us about 1/3 the time if we used our backup tapes & said `oh well' to the stuff after the last incremental backup. By the way, we are still using the volume set even after the disaster. The advantages of the volume set on a daily basis outweigh the problem we had this last holiday weekend. --Mark