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Hello,<br>
<br>
I'm currently testing setup where DRBD is used on top of ZFS (zvol).
Even worse, I'm using btrfs on top of DRBD device. I have this setup
working without problems until I'm doing heavy load tests. When I'm
trying to do bulk write random files to file system (btrfs on DRBD)
I see sometimes messages similar to the one below:<br>
<br>
<pre>Apr 30 11:31:29 srv2 kernel: d-con diskless-nfs: [drbd_w_diskless/31594] sock_sendmsg time expired, ko = 6</pre>
<br>
I know that this most likely indicates physical network issues, but:<br>
- I don't have any problems under heavy loads until I use ZFS
instead LVM<br>
- "ip -s link dev..." doesn't show any errors or dropped packages<br>
- while doing tests I'm running ping from another node and can't see
any delays or dropped packets<br>
<br>
Machines have two Gb network interfaces one is dedicated to DRBD.
I'm running gkrellm monitor form my workstation to see the "the
whole picture" and the strange thing is that while I see errors
above the gkrellm monitor is frozen for a few seconds, but then
resumes and works fine again.<br>
<br>
I know this setup is a kind of... strange, but still. I'd appreciate
any help with this. Maybe it's necessary to tune some DRBD
parameters when using on top of ZFS, particularly disk related.<br>
<br>
Currently I'm running vanilla kernel 3.8.8 with drbd-8.4.2. The DRBD
device setup is below:<br>
<br>
<font face="monospace">resource diskless-nfs {<br>
options {<br>
}<br>
net {<br>
protocol A;<br>
}<br>
_remote_host {<br>
address ipv4 192.168.2.1:7830;<br>
}<br>
_this_host {<br>
address ipv4 192.168.2.2:7830;<br>
volume 0 {<br>
device minor 30;<br>
disk "/dev/pool/diskless-nfs";<br>
meta-disk internal;<br>
disk {<br>
fencing resource-only;<br>
resync-rate 15360k; # bytes/second<br>
}<br>
}<br>
}<br>
}</font> On the primary node I'm using SSD as L2ARC ZFS read cache
and with DRBD protocol A it performs very well. Hopefully somebody
else would be interested in this setup as well.<br>
<br>
Regards,<br>
Vlad.<br>
<br>
<br>
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