[comp.unix.questions] validation of dumps

linda@cc.brunel.ac.uk (Linda Birmingham) (02/02/89)

I'm interested in knowing how many sites validate their dump tapes after
dumping. In over 2 years with appx 6GB of disk space we have had only one
problem retrieving a file. This makes me think it would be unecessary to
spend twice as long dumping by including a validation process. I think
it may be sensible to check  a few dump tapes chosen at random from
the tape library.

Any comments anyone ?

Linda.

-- 
Brunel University, Uxbridge, Middlesex, England.
janet: linda@uk.ac.brunel.cc |  :-)
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peno@kps.UUCP (Pekka Nousiainen /DP) (02/10/89)

>I'm interested in knowing how many sites validate their dump tapes after
>dumping.

We dump 2 GB on monthly/weekly/daily levels and do not validate the tapes.
I would like to add a readback of the dump header to the operator scripts
(no doubt over much griping from operators).  When I move file systems I
always make 2 tape copies before wiping out the disk.  This has saved me
once, when moving a 1 GB production file system.

Our main concern is the daily backup of a 3 GB database (on raw disks).
If one tape fails, the entire backup is useless.  The backup already takes
2 1/2 hours.  A readback-and-verify is an option but is never used.  Has
anybody figured out a failure rate for reel-to-reel tapes?  I think about
1 tape in 100 does fail on our system.  The machine is a Pyramid 9020 with
a Fujitsu tape drive, the tapes are 3M and others.

Then there is the question of video tapes where I still don't know who's
opinion to believe...

--
peno@kps

zeeff@b-tech.ann-arbor.mi.us (Jon Zeeff) (02/12/89)

It seems that what we need is a backup program that does error 
correction on large blocks when reading from tapes (or any other 
device).  I've used programs for a PC where you can backup files to a 
floppy, punch a hole in the floppy, and still get all your data back. 
It's done with a very small increase in size.  


-- 
  Jon Zeeff			zeeff@b-tech.ann-arbor.mi.us
  Ann Arbor, MI			mailrus!b-tech!zeeff