From: John G. <jgo...@co...> - 2011-02-23 16:40:25
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Michael Stowe <mstowe <at> chicago.us.mensa.org> writes: > Another way to put this is that you'd like BackupPC to overcome > performance problems caused by your amazingly slow I/O. Not that I'm > arguing against rewriting BackupPC to accomodate slow media, but I'm > certainly not going to bother, since it's certainly not slow for me. Well, I don't think that's entirely accurate. BackupPC is on the order of 10 times slower than alternatives making full backups after the first. It is on the order of 20-50 times slower than alternatives making incrementals. This referring to the same disk setup. The order of magnitude here won't go away with faster disks. If, say, the disks are twice as fast, then it could still be 10 times slower but maybe that wouldn't be as much a problem. I've also noted performance problems using BackupPC+rsync to back up 25GB files, and that on enterprise server-class hardware, not my personal USB drive at home. I believe I've found a design issue in how BackupPC uses rsync, but I'm not clever enough yet to work out what it is or if/how I could work around it. > Might I suggest that you back up to something quicker, and then copy it > over to your USB drive? (If that's too slow, than I fail to see how > BackupPC can do any better.) I don't expect that to be worth the expense. In other words, half of 55 hours is still too long. The only thing I think that can improve this is switching to tar, but then I have the problem I'm mentioning in the other thread. -- John |