On 09/26/2012 02:35 PM, Stephen Thompson wrote:
> 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 think I pointed this out before, but I also have used and new tapes
with 400-800Gb on them. It seems really hit or miss, though the tapes
with 400Gb or less are probably a 1/3 of my tapes. The other 2/3 have
above 400Gb.
>
> 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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