Re: [Bacula-users] Mistaken append of job to media

On 06/07/11 12:14, Rory Campbell-Lange wrote:
> On 07/06/11, Phil Stracchino (alaric AT metrocast DOT net) wrote:
>> On 06/07/11 09:59, Rory Campbell-Lange wrote:
>>> I've written job 329 after job 315 on the same tape (CLW112L4). See below
>>>
>>> Two questions:
>>>
>>>     * can I wipe the data pertaining to job 329 off tape CLW112L4 ?
>>>       (I assume by using mt commands -- how can I find the block number
>>>        to start writing zeros from?)
>>
>> Not safely, no.  But you could migrate the second job to a different
>> volume, or delete the job and re-run it to a different volume.
> 
> Does deleting the job remove the data (in this case the data for job
> 329) off the tape? That is what I need to do.

No, it doesn't.  But you've already said you weren't planning to append
anything else to that tape ... right?  As long as the data is copied to
where it should be, and logically (at least) purged from that tape, does
it matter?  Will the tape take up more space in the library because the
end of the tape has been written once with now-discarded data?  Do the
extra 1 bits make the tape heavier?

If it's really, really important to you that no trace of job 329 remain
on that tape, then you need to migrate both job 315 AND job 329 to new
media, then purge the old media, manually erase it from beginning to end
with something like mt, and then relabel it.  But if it's really that
important to you that no trace of data from one job ever remain on a
tape used by another, then you need to be erasing and relabelling your
tapes between EVERY use.[1]  I'm going to go out on a limb here and
guess that you probably don't actually want or need to be doing that.


[1]  And frankly, three-letter agencies that really DO have needs like
that are far more likely to just bulk-erase their once-used tapes, shred
them, incinerate the remains, and stir the ashes.

-- 
  Phil Stracchino, CDK#2     DoD#299792458     ICBM: 43.5607, -71.355
  alaric AT caerllewys DOT net   alaric AT metrocast DOT net   phil AT 
co.ordinate DOT org
  Renaissance Man, Unix ronin, Perl hacker, SQL wrangler, Free Stater
                 It's not the years, it's the mileage.

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