lmjm@doc.ic.ac.uk (Lee McLoughlin) (12/06/88)
Just curious as to how people do backups out there. I only have a 1.2Meg floppy drive. Most of my discs have some kind of problem with them (my disc budget is low, ok its 0). I can't see any easy way to backup to disks with faults. Using tar + vol wouldn't necessarily work as vol doesn't do a write+read check to see if the data got out there correctly. I've not found anything in the minix kernel to do such a check either. Before anyone tells me to go and buy decent discs do bear in mind that the problem of restoring discs is one you may all have to face. A backup disc can be corrupted by a wide range of environmental conditions (tea, coffee, children, footprints...) and vol will just stop at the first problem. L -- -- Lee McLoughlin 01 589 5111 X 5028 Department of Computing,Imperial College,180 Queens Gate,London SW7 2BZ Janet: lmjm@uk.ac.ic.doc Uucp: lmjm@icdoc.UUCP, ukc!icdoc!lmjm DARPA: lmjm@doc.ic.ac.uk (or lmjm%uk.ac.ic.doc@nss.cs.ucl.ac.uk)
dtynan@sultra.UUCP (Der Tynan) (12/08/88)
In article <LMJM.88Dec5222005@oriona.doc.ic.ac.uk>, lmjm@doc.ic.ac.uk (Lee McLoughlin) writes: > 1.2Meg floppy drive. Most of my discs have some kind of problem with > them (my disc budget is low, ok its 0). I can't see any easy way to > backup to disks with faults. Using tar + vol wouldn't necessarily > work as vol doesn't do a write+read check to see if the data got out > there correctly. Don't waste your time, your money or your disks, if this is your attitude toward doing backups. Writing a backup to a dubious disk is about as good as directing it to /dev/null, and a lot slower. A lot of things change on a disk and in a diskdrive over time, and none (well, almost none) of them improve the performance. A disk, which today shows 10% bad blocks will probably produce 15 -> 20%, when you want the data back (thanks, Mr Murphy :-) Checking the disk when you write it isn't enough. You have to have a lot of confidence in the media manufacturer, that bad blocks won't show up later on. Remember, a backup disk may be your only salvation if your hard-disk dies, taking with it, your PhD thesis, or worse, your online "little black book". > Before anyone tells me to go and buy decent discs do bear in mind that > the problem of restoring discs is one you may all have to face. A > backup disc can be corrupted by a wide range of environmental > conditions (tea, coffee, children, footprints...) and vol will just > stop at the first problem. > > Lee McLoughlin 01 589 5111 X 5028 A backup disk is sacred. It should be locked away in a jewel-encrusted gold box, along with your 49-ers autographs. The fact that it's possible to spill coffee on a disk is no justification for using cheap disks. If your kids have access to your backup medium, it isn't much of a backup. It is generally accepted, that in the rare event (?) you lose your hard disk, there's always the backup tape. If your tape has errors, then you're SOL! You have two places to store the critical information. You're spreading your risk. If *both* copies get screwed up, you did something wrong. However, if in the horrible and hopefully rare instance, that you *do* have errors on your backup medium, I would suggest using some sort of dumb copy (dd perhaps) to a decent disk, and try again. Remember, though, that UN*X tar has checksums to prevent destroying an FS with a bad tape. You'll also have to get around that. - Der -- dtynan@zorba.Tynan.COM (Dermot Tynan @ Tynan Computers) {apple,mips,pyramid,uunet}!Tynan.COM!dtynan --- If the Law is for the People, then why do we need Lawyers? ---