bob944 wrote:
>>> Dudes is there any way of saying how much space is left
>>> on a particular tape? I have had a look around but am a
>>> bit lost.
>>>       
>> Yeah, run bpmedialist and compare with vmquery.
>>     
>
> That answer makes no sense.
>
> Dave, a tape holds as much as it holds, period.
>
> In contrast to a disk (has _exactly_ so many cylinders/tracks/sectors
> and is usually not compressed); tapes write varying lengths of data,
> separated by gaps of different sizes; usually compressing data with
> variability in the data, in its fit in the drive buffer, in the firmware
> algorithm on that drive; with unpredictable skips over flawed patches of
> tape; and to tape length which is not uniform.  The same tape, written
> in the same drive with the same source data can vary; the same tape,
> same drive, backing up something different will likely be quite
> different.  Throw in the variables and and... well, I've seen a range of
> 4xxGB to 12xxGB on full SDLT600 tapes, for instance.
>
> An available_media listing with a bunch of full tapes will show you the
> variability and give you a rough guide of what to expect from a given
> pool and retention (more variability if you use one pool for many/all
> types of backups, less if you have pools which handle specific clients
> and specific, non-volatile data).
>
> When a tape hits EOM (Simon:  End Of Medium to your question; used to be
> End Of Tape by detecting a foil sticker) and NetBackup moves on to
> another tape, you have zero space left.  Anything else is an
> approximation.
>
>
>   
THanks for that. Was king of thinking that myself from looking at
bpmedialist and seeing some tapes which were full had less than others.
I guess it depends how much the data on disk took up but can be
compressed onto the tape. Some files are perhaps already compressed and
so that particular job used a certain tape and the compression could not
be made any more.

Thanks

I was just trying to work out which tapes to take out as i have 4 in one
volume pool and i only need 1 really ( as its for logs ) so didn't want
to take one out with loads of space left on it.

I was just wondering if there was something which said although certain
amount of the tape is used as its a DLT  35/70 it has X kb left.

Cheers