[Gluster-users] Gluster write speed depends on bs

[Johan Huysmans]

Hi All,

I'm performing some speed tests on my simple gluster setup.
There is only 1 node and the mountpoint uses the glusterfs daemon.

# gluster volume info
Volume Name: testvolume
Type: Distribute
Volume ID: 9476ee38-33d3-4e98-9649-2e150b92d26e
Status: Started
Number of Bricks: 1
Transport-type: tcp
Bricks:
Brick1: SRV-1:/gluster/brick1
Options Reconfigured:
network.ping-timeout: 5
performance.stat-prefetch: off


# mount | grep gluster
/dev/mapper/systemvg-gluster on /gluster type xfs (rw)
localhost:/testvolume on /mnt/sharedfs type fuse.glusterfs 
(rw,default_permissions,allow_other,max_read=131072)

When I perform writes to the /gluster directory (this is the xfs 
partition where the brick is located) I get these speeds:
# dd if=/dev/zero of=/gluster/test bs=8k count=128k conv=fsync
131072+0 records in
131072+0 records out
1073741824 bytes (1.1 GB) copied, 6.61025 s, 162 MB/s

# dd if=/dev/zero of=/gluster/test bs=128k count=8k conv=fsync
8192+0 records in
8192+0 records out
1073741824 bytes (1.1 GB) copied, 6.43005 s, 167 MB/s

When I perform the same test on the glusterfs mountpoint I get following 
results:
# dd if=/dev/zero of=/mnt/sharedfs/test bs=8k count=128k conv=fsync
131072+0 records in
131072+0 records out
1073741824 bytes (1.1 GB) copied, 22.7804 s, 47.1 MB/s

# dd if=/dev/zero of=/mnt/sharedfs/test bs=128k count=8k conv=fsync
8192+0 records in
8192+0 records out
1073741824 bytes (1.1 GB) copied, 9.43556 s, 114 MB/s


What I see is that the bs makes a big difference in speed.

What must I do to receive high write speeds with small blocks ?
Is this configurable with some option ?

Thx!

Greetings,
Johan Huysmans