On 09/25/2012 02:29 PM, Cejka Rudolf wrote:
> Stephen Thompson wrote (2012/09/25):
>> The tape in question have only been used once or twice.
>
> Do you mean just one or two drive loads and unloads?
>
Yes, I mean the tapes have only been in a drive once or twice, possibly
for a dozen sequential jobs while in the drive, but only in and out of
the drive once or twice.
I have seen this 200-300Gb capacity on new tapes as well as used.
I see it in both my SL500 library as well as my C4 library, which is a
combined 4 LTO3 drives (2 in each library).
>> The library is a StorageTek whose SLConsole reports no media (or drive)
>> errors, though I will look into those linux-based tools.
>
> There are several types of errors, recoverable and non-recoverable, and
> I'm afraid that you see just non-recoverable, but it is too late to see
> them.
>
>> Our Sun/Oracle service engineer claims that our drives do not require
>> cleaning tapes. Does that sound legit?
>
> If you are interested, you can study
> http://www.tarconis.com/documentos/LTO_Cleaning_wp.pdf ;o)
> So in HP case, it is possible to agree. However, you still
> have to have atleast one cleaning cartridge prepared ;o)
>
>> Our throughput is pretty reasonable for our hardware -- we do use disk
>> staging and get something like 60Mb/s to tape.
>
> HP LTO-3 drive can slow down physical speed to 27 MB/s, IBM LTO-3
> to 40 MB/s. Native speed is 80 MB/s, bot all these speeds are after
> compression. If you have 60 MB/s before compression and there are
> some places with somewhat better compression than 2:1, then you are not
> able to feed HP LTO-3. For IBM drive, it is suffucient to have places
> with just 2:1 to need repositions.
>
>> 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).
>
> And what about the reason to switch to the next tape? Do you have something
> like this in your reports?
>
> 22-Sep 02:22 backup-sd JobId 74990: End of Volume "1" at 95:46412 on device
> "drive0" (/dev/nsa0). Write of 65536 bytes got 0.
> 22-Sep 02:22 backup-sd JobId 74990: Re-read of last block succeeded.
> 22-Sep 02:22 backup-sd JobId 74990: End of medium on Volume "1"
> Bytes=381,238,317,056 Blocks=5,817,238 at 22-Sep-2012 02:22.
>
Here's an example of a tape that had one job and only wrote ~278Gb to
the tape:
10-Sep 10:08 sd-SL500 JobId 256773: Recycled volume "FB0095" on device
"SL500-Drive-1" (/dev/SL500-Drive-1), all previous data lost.
10-Sep 10:08 sd-SL500 JobId 256773: New volume "FB0095" mounted on
device "SL500-Drive-1" (/dev/SL500-Drive-1) at 10-Sep-2012 10:08.
10-Sep 13:02 sd-SL500 JobId 256773: End of Volume "FB0095" at 149:5906
on device "SL500-Drive-1" (/dev/SL500-Drive-1). Write of 262144 bytes
got -1.
10-Sep 13:02 sd-SL500 JobId 256773: Re-read of last block succeeded.
10-Sep 13:02 sd-SL500 JobId 256773: End of medium on Volume "FB0095"
Bytes=299,532,813,312 Blocks=1,142,627 at 10-Sep-2012 13:02.
> Do not you use something from the following things in bacula configuration?
> UseVolumeOnce
> Maximum Volume Jobs
> Maximum Volume Bytes
> Volume Use Duration
> ?
>
No, none of those are configured.
Stephen
--
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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