On 10/01/2012 03:52 PM, James Harper wrote:
>>
>> Hi,
>>
>> I ran some btape tests today to verify that I'd be improving throughput by
>> changing blocksize from 256KB to 2MB and found that this does indeed
>> appear to be true in terms of increasing compression efficiency, but it
>> doesn't seem to affect incompressible data much, if at all.  Still, it seems
>> worth changing and I thank you for pointing me in that direction.
>>
>> More importantly, I realized that my testing 6 months ago was not on all
>> 4 of my drives, but only 2 of them.  Today, I discovered one of my drives
>> (untested in the past) is getting 1/2 the throughput for random data writes 
>> as
>> the others!!
>>
>
> Is it definitely LTO3 and definitely using LTO3 media? LTO2 was about half 
> the speed, including using LTO2 media in an LTO3 drive.
>
> James
>

Yes, all 4 drives are HP Ultrium 3 drives.
And the same LTO3 bacula volume was used in all 4 testing runs today.
All drives are connected via 2Gb fiber.
All tests were done independent of each other with no other activity on 
the backup server during the time of the testing.


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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