Hello...

I seem to remember a feature request for delaying the start of writing to tape until X%/Xbytes are done dumping and ready to write. It was on sourceforge? zmanda wiki? I cannot seem to find it now. Does anyone know where it was?

Writing 500M to a 800G tape is irritating. I would be willing to sponsor a developer to work on this. Any takers?

--
Christopher McCrory
"The guy that keeps the servers running"

To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

Christopher McCrory wrote:
> Hello...
>
> I seem to remember a feature request for delaying the start of
> writing to tape until X%/Xbytes are done dumping and ready to
> write. It was on sourceforge? zmanda wiki? I cannot seem to
> find it now. Does anyone know where it was?
>;
> Writing 500M to a 800G tape is irritating. I would be willing
> to sponsor a developer to work on this. Any takers?

I can see two ways this option would be useful.
First, by having taper wait until 100% of the dumps are finished,
it would avoid the contention on the holding disk and potentially
enable faster streaming to the tape drive, at the expense of needing
enough disk space to hold your entire backup. It could also make
better use of the tape space if my taperorder suggestion below was
implemented.
Second, if you have small backups and large tapes, you could set
it to 90% or so and have Amanda only use a tape when you have run
enough dumps to mostly fill a tape. This might have some interaction
with the autoflush parameter, however.
Also, on a somewhat related note, if taper were to wait until
all the dumps finished, and runtapes is greater than 1, could there
be a taperorder parameter similar to dumporder that would do a
largest-fit write to tape, and avoid trying to write a dump too
large to fit in the remaining space on a tape? I haven't dug in
the code, but taper just seems to work in a FIFO fashion, and
writes until it hits EOT and then starts anew on the next tape with
the failed dump. For runtapes = 2, largest fit would be sufficient,
but for runtapes >=3 perhaps another strategy would be better,
although possibly not by enough to justify the extra code.

Frank

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