> > > > If you care enough to do backups, at least care enough to be > > able to restore. For my home backups, I use portable drives with > > copies=2 or 3 and compression enabled. I don't fool with > > incrementals, but many people do. The failure mode I'm worried > > about is decay, as the drives will be off most of the time. The > > copies feature works well for this failure mode. > > I am definitely and strongly interested in restoring! That's why I hate > my previous backup solutions so much (NTI backup and then Acronis True > Image); I verified backups and tested restores, and had *FAR* too much > trouble to be at all comfortable. The photos and the ebooks are backed > up eventually (but not always within the month) to good DVDs, and one > copy is kept off-site, and that's the stuff I'd miss most if it went, > but I want a good *overall* solution. > > The "copies" thing sounds familiar from discussion here...ah. Yes, > that's exactly perfect; it lets me make up a batch of miscellaneous > spare disks totaling enough space, each one a vdev, put them into one > pool (no redundancy), but with copies=2 get nearly the redundancy of > mirroring which would have required matching drives. At least, if I
>From what I have seen I think you are over estimating the value of copies=x. copies=X are guaranteed to store multiple copies (X) of the blocks _somewhere_ in the pool, but not necessarily on different disks. So while you may gain mirror like protection when you have failed blocks on a disk (maybe -- blocks could be too close together on the same disk); you do not necessarily gain that from a failed disk (block copies could be on only one disk). Having different sized unprotected disks and using copies=N has less mirror like effect over time and fragmentation of those disks. http://blogs.sun.com/bill/entry/ditto_blocks_the_amazing_tape http://blogs.sun.com/relling/entry/zfs_copies_and_data_protection copies < mirrors. > find a solution for connecting that bunch of disks conveniently. I > really want one box with easily swappable disks, and one cable. (And > then two of them, since of course I need two sets of backup media to > alternate between.) And I could update the old full backup to become > the new one using rsync locally, perhaps much faster than doing a full CP. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
