On 03/31/10 10:39, Josh Fisher wrote:
> On 3/30/2010 5:44 PM, William Taylor wrote:
>
>> Before enabling encryption we were getting 118 - 120 MBs throughput to our
>> LTO-4 tape drive.
>> With encryption turned on we get 38-39MBs throughput. bacula process is at
>> 98 - 100 % cpu while running.
>> I tried cutting the key size down to 472bits from 2048bits but it didn't
>> make a difference.
>> The machine is a 2.3 Ghz quad core xeon w/ 12GB of ram.
>> Everything is ran on one machine. (dir,fd,etc..)
>>
>> Any ideas whats up or how I can improve speed of backups w/ encryption
>> enabled?
>>
>> Thanks,
>> William
>>
>>
>>
> Without encryption hardware, it likely is a high CPU load. I don't
> believe the encryption itself is multi-threaded. By 98-100% cpu, do you
> mean for one core or all 4?
>
>
Correct, the encryption code is not multi-threaded (the same goes for
compression). In addition, hardware crypto accelerators are not
supported by Bacula. Bacula does not supports OpenSSL engine selection
- my feeble attempts at adding this resulted in strange crypto init
failures that I was unable to diagnose. Also, I've tried a handful of
fairly recent crypto cards and the performance is nothing exciting when
compared to any recent CPU. They are actually much much worse than any
modern CPU if you are encrypting small blocks of data at a time.
> Are you using spooling? Because the delay caused by encryption could
> cause the tape drive to be outrunning the data stream. If it has to
> start and stop repeatedly it would drastically affect throughput, and
> spooling could be a huge improvement.
>
>
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