Hi Kurt,

Kurt Yoder wrote:

<cites cut>

Couldn't "append to tape" be simulated? That is, rewind the tape and
check the tape label as normal. Then copy all contents of the tape
to the holding disk. Then use amdump to add to the holding disk.
Then flush the holding disk back to tape. The drawback to this
solution is that it would take quite a bit longer. However, there
would be no risk of accidentally overwriting portions of the tape.

I'm just asking in theory; I have no plans to implement anything
like this at my site.

This idea might be more expensive even in terms of direct money:
all that winding eats your tape head (with most tape drives)
and the magnetic film on the tapes.

Especially the film at start of the tape is scrubbed more times.
Every tape should only be used N times, then replaced by a new one.

Thus your suggested approach doesn't help in any way saving tapes/money.
The tape usage count for _every_ backup doubles (ignoring label
reading / writing):
- with Amanda, as is, you need:
  1) 1 write (all partitions)                     1
  2) 1 rewind (tape drive on eject)               2
- with 'simulated' you need:
  1) 1 read (all partitions)                      1
  2) 1 rewind                                     2
  3) 1 write (all partitions)                     3
  4) 1 rewind (tape drive on eject)               4

You have to replace your tapes 2 times as often as with Amanda
as is, DOUBLING your tape cost, PLUS doubled cleaning tape cost
PLUS the cost to repair/replace your tape drive in half of the time.

Not to mention all the problems pointed out by others before.

regards

Georg
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