Re: [TUHS] Abstractions

Greg Woods responds to my posting: I meant "dump" as a generic verb, not specifically the Unix dump utility. Many sites also used tar to backup directory trees: after all, tar means Tape ARchiver. That was, however, contingent on a reliable signal from the tape unit, and my strong recollection is that when we moved to various types of cheap cassette tapes, the end-of-tape indicator was unreliable. Thus, we paid attention to both disk and tape sizes. Today, with 10TB+ on LTO-8 tapes, it isn't an issue for us, and we also tend to have many different ZFS volumes representing various parts of the filesystem, allowing different backup and snapshotting policies. Besides tapes and snapshots, we also have a live SAN mirror, and a remote snapshot server, giving plenty of data replication, and the warm fuzzy feelings from that. After 20 years of ZFS, I don't recall us ever losing data. We have also gone through two generations of major fileserver upgrades and complete data migrations without service interruptions (except for a brief interval for each user account to synchronize data on old and new servers). ------------------------------------------------------------------------------- - Nelson H. F. Beebe Tel: +1 801 581 5254 - - University of Utah FAX: +1 801 581 4148 - - Department of Mathematics, 110 LCB Internet e-mail: beebe(a)math.utah.edu - - 155 S 1400 E RM 233 beebe(a)acm.org beebe(a)computer.org - - Salt Lake City, UT 84112-0090, USA URL: http://www.math.utah.edu/~beebe/ - -------------------------------------------------------------------------------