Hello,
I have setup two Vmware virtual machines to replicate their storage with DRBD
using protocol C. So far the write performance isn't as good as I had hoped.
I have tested write performance using fio and right now the best I can get is
write throughput and IOPS that are about 50-75% as good as with drbd
replication disabled.
My setup is two identical Centos 5.5 VMs running drbd 8.3.8. The link between
them is two dedicated 10Gb adapters, no switch in between. I feel the link is
not the bottleneck but something in my drbd config.
I have followed the tuning recommendations on the linbit site and have seen
some small improvements, but still don't have the performance I was hoping for.
I thought I would be able to get a write penalty more like 10%, not the 25-50%
I am seeing.
I added no-disk-flushes; and no-md-flushes;.
I set max buffers and max-epoch-size to 8196, and also experimented with
several unplug-watermark sizes.
I also set my hardware RAID controller to 100% write cache.
I attached my drbd.conf. Any other ideas would be most appreciated. Thank you
Sean
global {
usage-count no;
}
common {
syncer { rate 200M; }
}
resource disk01 {
protocol C;
handlers {
pri-on-incon-degr "echo O > /proc/sysrq-trigger ; halt -f";
pri-lost-after-sb "echo O > /proc/sysrq-trigger ; halt -f";
local-io-error "echo O > /proc/sysrq-trigger ; halt -f";
}
startup {
degr-wfc-timeout 120;
}
disk {
on-io-error detach;
}
net {
after-sb-0pri disconnect;
after-sb-1pri disconnect;
after-sb-2pri disconnect;
rr-conflict disconnect;
}
syncer {
al-extents 3389;
}
on node01 {
device /dev/drbd0;
disk /dev/sdb;
address 192.168.69.11:7788;
meta-disk internal;
}
on node02 {
device /dev/drbd0;
disk /dev/sdb;
address 192.168.69.12:7788;
meta-disk internal;
resource disk02 {
protocol C;
startup {
wfc-timeout 0;
degr-wfc-timeout 120;
}
disk {
on-io-error detach;
no-disk-barrier;
no-disk-flushes;
no-md-flushes;
}
net {
# timeout 60;
# connect-int 10;
# ping-int 10;
max-buffers 8196;
max-epoch-size 8196;
unplug-watermark 8196;
sndbuf-size 0;
}
syncer {
after "cluster_metadata";
al-extents 3389;
}
on Node01 {
device /dev/drbd1;
disk /dev/sdc;
address 192.168.69.11:7789;
meta-disk internal;
}
on node02 {
device /dev/drbd1;
disk /dev/sdc;
address 192.168.69.12:7789;
meta-disk internal;
}
}
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