On 09/25/2012 10:43 AM, Alan Brown wrote:
> On 25/09/12 17:43, Stephen Thompson wrote:
>> Our Sun/Oracle service engineer claims that our drives do not require
>> cleaning tapes.  Does that sound legit?
>
> In general: true (as in, "Don't do it as a scheduled item"), but all LTO
> drives require cleaning tapes from time to time and sometimes benefit
> from loading one even if the "clean" light isn't on. It primarily
> depends on the cleanliness of the room where the drive is.
>
>> Our throughput is pretty reasonable for our hardware -- we do use disk
>> staging and get something like 60Mb/s to tape.
>
> 60Mb/s is _slow_ for LTO3. You need to take a serious look at what
> you're using as stage disk and consider using a raid0 array of SSDs in
> order to keep up.
>
>> Lastly, the tapes that get 200 vs 800 are from the same batch of tapes,
> same number of uses, and used by the same pair of SL500 drives.  That's
> primarily why I wondered if it could be data dependent (or a bacula bug).
>
>
> What happens if you mark the volumes as "append" and put them back in
> the library?


I haven't had a lot of time to look into this today, but I do this quick 
test and it immediately marks the volume Full again.

27-Sep 14:20 sd-SL500 JobId 260069: Volume "FB0763" previously written, 
moving to end of data.
27-Sep 14:21 sd-SL500 JobId 260069: Ready to append to end of Volume 
"FB0763" at file=110.
27-Sep 14:21 sd-SL500 JobId 260069: Spooling data ...
27-Sep 14:21 sd-SL500 JobId 260069: Job write elapsed time = 00:00:01, 
Transfer rate = 759.3 K Bytes/second
27-Sep 14:21 sd-SL500 JobId 260069: Committing spooled data to Volume 
"FB0763". Despooling 762,358 bytes ...
27-Sep 14:21 sd-SL500 JobId 260069: End of Volume "FB0763" at 110:1 on 
device "SL500-Drive-0" (/dev/SL500-Drive-0). Write of 262144 bytes got -1.
27-Sep 14:21 sd-SL500 JobId 260069: Re-read of last block succeeded.
27-Sep 14:21 sd-SL500 JobId 260069: End of medium on Volume "FB0763" 
Bytes=219,730,936,832 Blocks=838,207 at 27-Sep-2012 14:21.
27-Sep 14:21 sd-SL500 JobId 260069: 3307 Issuing autochanger "unload 
slot 36, drive 0" command.




>
> I've seen transient scsi errors result in tapes being marked as full.
>
> What does smartctl show for the drive and tape in question? (run this
> against the /dev/sg of the tape drive)
>
>
>


-- 
Stephen Thompson               Berkeley Seismological Laboratory
stephen AT seismo.berkeley DOT edu    215 McCone Hall # 4760
404.538.7077 (phone)           University of California, Berkeley
510.643.5811 (fax)             Berkeley, CA 94720-4760

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