Re: tape drives

[Adam Tauno Williams <adam@xxxxxxxxxxxxxxxx>]

>>>>a backup-software skeptic.
>>>The problem with tar and cpio that the better commercial backup software
>>>corrects is that the commercial software verifies the tape after writing
>>>where tar doesn't.  It doesn't matter how fast your backup/restore is
>>>if you don't have a good backup and your data is corrupt.
>>I was told once that DDS tapes verify after writing in the hardware.
>If you look at the specs most tape drives just do a very simple verify,
>though I believe that the DLT drives are different.  I've seen tapes
>that were backed up with no errors that you were not able to read
>anything off them at all.  Just this last month, a user of mine wanted a
>file off a 8mm tar backup tape, and no matter what system we tried it on
>we were not able to read it.  If you have a regular backup schedule with
>rotating tapes you may be ok, but I would still try to go through and
>get at least a table of contents off the tape once in a while.  It all
>comes down to what your data is worth and the costs to re-create it.

We write the tar archive and record the table, then table the archive and 
compare the two results.  This is a relatively simple thing to script.

I'm curious about the "find a file quick" feature of some commercial software,  
are some able to do that without a "on-disk" catalog?