Andrew,
many thanks for this hint. I installed the IBM driver and found the tape drive
testing tool itdt, too.
Now, using itdt and the new driver there is an improvement:
LTO6: 158 MB/s without compression, 177MB/s with compression
LTO4: 27 MB/s without compression, 128 MB/s with compression.
For LTO6 this is in fact near to the theoretical limit (regarding random data).
Using btape with the new driver I still got 153MB/s (with compression) resp. 39
MB/s (random data).
Seems as if there is a bottleneck in bacula?
My device configuration:
Device {
Name = "LTO6-1"
Device Type = Tape;
Media Type = LTO6
Archive Device = /dev/IBMtape0n
AutomaticMount = yes;
AlwaysOpen = yes;
RemovableMedia = yes;
RandomAccess = no;
Spool Directory = /var/spool/bacula
Maximum Spool Size = 300G
Maximum File Size = 5G
Maximum Block Size = 1m
}
> Am 28.11.2015 um 08:56 schrieb Andrew Ryder <[email protected]>:
>
> Are you using the IBM Linux tape driver? If not, I'd suggest installing it vs
> the generic linux kernel's tape driver.
>
> http://www-933.ibm.com/support/fixcentral/swg/selectFixes?parent=Tape%2Bdrivers%2Band%2Bsoftware&product=ibm/Storage_Tape/Tape+device+drivers&release=1.0&platform=Linux&function=all
>
> On 11/27/2015 08:43 AM, Christoph Litauer wrote:
>> Dear bacula users,
>>
>> I recently recognized that my tape drives do not perform as expected.
>> Neither while used with bacula nor native with dd. I did many performance
>> tests in the meantime but could not figure out the reason. So may I ask in
>> this group what typical write speeds you have with your tape drives?
>>
>> I tested LTO6 (IBM Ultrium HH6) and LTO4 (Ultrium 4-SCSI). Both are part of
>> two libraries connected via SAS to a LSI SAS3801E-controller. The host
>> system runs SLES12.
>> I used btape and dd for writing.
>> I figured out the best writing performance with blocksize 512KB (LTO4) resp.
>> 2MB (LTO6). Both drives with compression on.
>>
>> LTO4 best performance (writing zeros): 115 MB/s
>> LTO4 worst performance (random data): 71.58 MB/s
>>
>> LTO6 best performance (zeros): 153 MB/s
>> LTO6 worst performance (random): 58 MB/s
>>
>> Disabling compression does not change the maximum speed. In this case
>> writing zeros is the same as writing random date (expected).
>>
>> According to Wikipedia, theoretical speed should be
>> LTO4: 240 resp. 120MB/s
>> LTO6: 400 resp. 160MB/s
>>
>> Any ideas welcome! Thanks in advance!
>>
>> --
>> Kind regards
>> Christoph
>> _________________________________________
>> Christoph Litauer
>> Uni Koblenz, Computing Centre, Office A 022
>> Postfach 201602, 56016 Koblenz
>> Fon: +49 261 287-1311, Fax: -100 1311
>>
>>
>>
>>
>> ------------------------------------------------------------------------------
>> _______________________________________________
>> Bacula-users mailing list
>> [email protected]
>> https://lists.sourceforge.net/lists/listinfo/bacula-users
>>
--
Freundliche Grüße
Christoph Litauer
_________________________________________
Christoph Litauer
Uni Koblenz, Rechenzentrum, Raum A 022
Postfach 201602, 56016 Koblenz
Fon: +49 261 287-1311, Fax: -100 1311
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