Hi all,

I searched the archives and found a thread on bacula-users from Dec07 with 
subject "LTO-4 backup rates", and also a thread on bacula-devel from Sep07 with 
subject "Bacula performance with a 64512 block size".

I just got a new IBM TS3310 with 3 LTO-4 SAS drives, and after my initial 
Bacula setup, I'm getting ~23MB/s writing to the drive.

I have verified that the local disk is not the bottleneck as well as the actual 
source (a SAN volume via 10gigE) as bonnie++ gets me numbers as high as 
330MB/s.  I have also verified that I can write to all three drives at once 
(~24MB/s each) and otherwise load the server (disk I/O, CPU) without affecting 
the 23MB/s write rate.  It seems like writing to the tape drive is the 
bottleneck.

Asking on another forum I got a suggestion to increas the "block size" and 
"buffer size", but it is not clear to me how to do that with my hardware and 
Bacula.

I see the "Maximum Network Buffer Size" directive, and I'll try testing the 
performance with different values for that, but is there anything else I can 
tweak?  Another thread I found in the archive suggests that the current default 
buffer size is 64KB.

We were consistently getting ~60MB/s to our LTO-3 drives with older hardware 
and Bacula, so I was hoping for ~120MB/s.

This isn't specifically a Bacula software problem, I'm getting ~23MB/s with 
"btape fill".  This is Bacula 2.2.8 on CentOS 5.1 on an IBM x3650.

Any suggestions? 

Thanks,
-- 
Alex Chekholko

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