russ@wpg.UUCP (Russell Lawrence) (02/03/89)
Does anyone know of any PD dump/dumpdir/restor programs persistent
enough to skip over bad spots on tape?
Thanks.
--
Russell Lawrence, WP Group, New Orleans (504) 443-5000
{uunet,killer}!wpg!russchilders@avsd.UUCP (Richard Childers) (02/10/89)
In article <1084@wpg.UUCP> russ@wpg.UUCP (Russell Lawrence) writes: >Does anyone know of any PD dump/dumpdir/restor programs persistent >enough to skip over bad spots on tape? No, but I know of a few ways to test for bad spots on tape, if it's something you've got the time and energy to be interested in. Caveat - testing for errors takes time, you almost have to do the dump twice and compare results before you can be *really* sure. The following methods represent a half-hearted approach to verification. 1) test the physical media of the tape dd if=/dev/rmt8 of=/dev/null bs=10k 2) test the internal consistency of the dump image by reading the bookkeeping data on it ( errors appear on stderr() ) restore -tf /dev/rmt8 > /dev/null 3) act according to the results of these tests by remaking the dump image if necessary. Two extra hours now can save the day later ... ... both of these methods working together are quite good, albeit expensive in time. But if you've got no other overriding responsibilities or can use your time very effectively, doing this in the background as part of the dump routine is an excellent way to guarantee good dump images. >Thanks. You're welcome. >Russell Lawrence, WP Group, New Orleans (504) 443-5000 >{uunet,killer}!wpg!russ -- richard -- * "Do not look at my outward shape, but take what is in my hand." * * -- Jalaludin Rumi, 1107-1173 * * ..{amdahl|decwrl|octopus|pyramid|ucbvax}!avsd.UUCP!childers@tycho * * AMPEX Corporation - Audio-Visual Systems Division, R & D *
russ@wpg.UUCP (Russell Lawrence) (02/11/89)
> In article <1084@wpg.UUCP> I wrote: > >Does anyone know of any PD dump/dumpdir/restor programs persistent > >enough to skip over bad spots on tape? In article <472@avsd.UUCP>, childers@avsd.UUCP (Richard Childers) writes: > No, but I know of a few ways to test for bad spots on tape, if it's something > you've got the time and energy to be interested in. > > Caveat - testing for errors takes time, you almost have to do the dump twice > and compare results before you can be *really* sure. The following methods > represent a half-hearted approach to verification... This is good advice. Unfortunately, I'm trying to recover files from a dump tape that was perfectly good a year ago when I made the dump, but got chewed up a little last week in my tape drive... thanks to some dirty rollers. As a result, the tape is now useless given the inability of dump to recover. I'm still hoping that someone will suggest a recovery procedure that will bail me out. Nevertheless, the experience has convinced me that I should abandon dump/restor and opt instead for ctar or pax.... given their ability to skip over bad spots. If I knew more about dump headers, I suppose I could hack something out that could look for the appropriate file on the tape (ie inode number) and retrieve the data. Any comments? -- Russell Lawrence, WP Group, New Orleans (504) 443-5000 {uunet,killer}!wpg!russ
linda@cc.brunel.ac.uk (Linda Birmingham) (02/21/89)
In article <1086@wpg.UUCP> russ@wpg.UUCP (Russell Lawrence) writes: >> In article <1084@wpg.UUCP> I wrote: >> >Does anyone know of any PD dump/dumpdir/restor programs persistent >> >enough to skip over bad spots on tape? > >In article <472@avsd.UUCP>, childers@avsd.UUCP (Richard Childers) writes: Advice on validation of dumps. Having had tape errors on a couple of tapes recently, we are becoming a little paranoid about dumps too. I thought about using dd as a validation method but we found that that read a particular tape error as end of file so to all intents and purposes the tape looked ok, except it only read 10 blocks %-}. I was also advised to restore the last file from a dump tape. That sounds a more rigorous validation to me. >I'm still hoping that someone will suggest a recovery procedure that will >bail me out. Nevertheless, the experience has convinced me that I >should abandon dump/restor and opt instead for ctar or pax.... given >their ability to skip over bad spots. Sounds interesting. > >If I knew more about dump headers, I suppose I could hack something out >that could look for the appropriate file on the tape (ie inode number) >and retrieve the data. Any comments? I think that's a good idea Russell, let me know when you've done it :-) Someone somewhere MUST have already done it though. BTW we also have a Pyramid 9820 with a Fujitsu tape drive. Linda. -- Brunel University, Uxbridge, Middlesex, England. janet: linda@uk.ac.brunel.cc | :-) uucp:...ukc!cc.brunel!linda |