Hi, I found the aggregated IO speed is only about 100MB/s on 4 Giga-bit Brick. This test is done over 12 computing nodes with command dd if=/dev/zero of=bar bs=1048576 count=20480. Because our brick has very fast local IO speed, the problem could be network. Then I found computing nodes got too many retransmited segments during test according to netstat -st. The retransmission ratio is about 5%, but brick node has a normally low transmission rate. Could some shed some light? Best, Manhong -------------- next part -------------- An HTML attachment was scrubbed... URL: http://zresearch.com/pipermail/gluster-users/attachments/20080823/302035d9/attachment.htm