[Bacula-users] LTO-3 getting the lead out.

Hi,
I am trying to improve my LTO-3 throughput.  I recently installed a SAS 
Tandberg LTO-3 drive.  I am using Bacula 3.0.3 in Ubuntu.  I backup to 
disk files, and then copy to tape.  The disk files are 4GB in size.  
They are stored on a 4 disk RAID 5 array.  The raid and the tape drive 
are in the same system.

dd'ing a file from the raid to /dev/null yields:
#dd if=vol-0572 of=/dev/null
8388576+1 records in
8388576+1 records out
4294951097 bytes (4.3 GB) copied, 45.0316 s, 95.4 MB/s

disabling compression on the tape drive, and
dd'ing the file from raid to /dev/nst1 yields:
#dd if=vol-0572 of=/dev/nst1 bs=64K
65535+1 records in
65535+1 records out
4294951097 bytes (4.3 GB) copied, 77.9708 s, 55.1 MB/s

enabling compression on the tape drive, and
dd'ing the file from raid to /dev/nst1 yields:
#dd if=vol-0572 of=/dev/nst1 bs=64K
65535+1 records in
65535+1 records out
4294951097 bytes (4.3 GB) copied, 43.1465 s, 99.5 MB/s

These are the copy job throughput rates.  The parent jobs of these three 
run concurrently, so all three jobs are in the same disk files.
Rate: 5GB @ 22282.1 KB/s
Rate: 8GB @ 22787.8 KB/s
Rate: 5GB @ 19648.1 KB/s

With the next two jobs, they do not run concurrent, so each disk file 
only contains the data of one job.
Rate: 290GB @ 25024.7 KB/s
Rate: 58GB  @ 27998.8 KB/s

This seems slower then it should be.

brian-



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