Journalling IO under ext4

Hi folks,

Moved a mailstore over ext4 the other day.

Total DISK READ: 8.16 M/s | Total DISK WRITE: 20.46 M/s

I'm seeing between 5-8MB/s reads and 12-20MB/s writes in iotop; with journaling being responsible for about 500K/s to 1MB/s+

2965 be/3 root 0.00 B/s 1428.82 K/s 0.00 % 56.50 % [jbd2/dm-1-8]

I know the amount of data journalled depends on what is being written, etc - but in general terms, does this seem like a normal level to anyone else with a similar high IO setup using ext4?

Cheers