Hi
On 11/22/2014 08:32 AM, Christian Völker wrote:
Hi,
I have a nearly default setup running. I moved the secondary drbd to a
VM at it appears to be incredibly slow.
I need some hints to troubleshoot why it is so slow. See the cat /proc/drbd:
GIT-hash: a798fa7e274428a357657fb52f0ecf40192c1985 build by
phil@Build64R6, 2013-09-27 16:00:43
0: cs:SyncTarget ro:Secondary/Primary ds:Inconsistent/UpToDate A r-----
ns:0 nr:38648 dw:38584 dr:0 al:0 bm:2 lo:16 pe:41 ua:1 ap:0 ep:1
wo:d oos:1677699908
[>....................] sync'ed: 0.1% (1638376/1638412)M
finish: 1792:24:51 speed: 244 (256) want: 250 K/sec
Speed of 244 is ways to slow. It ends up hours later with a io error on
the disk.
You should provide a bit more info:
- What cache strategy do you have on that VM ?
- What max write speed do you reach (ioflag=direct) ?
- Does the slow transfer rate happen only with DRBD or with other stuff ?
...
You may want to check the following things:
- play with the nic's driver checksumming options (on Virtualbox I had
very low transfer rates until I changed those options, but I don't
remember which one(s), and I don't use it anymore).
- use virtio drivers (both for disk and network)
- trivial, but check that you don't have accidentally have QoS rules
ivan
But when I check performance values I do not see any bottlenecks:
-CPU IO wait is below 2%
-CPU itself is ~98%idle
-network is not busy at all.
Anyone having a clue why this is so slow?
Here my drbd.res:
resource drbd0 {
protocol A;
startup {
wfc-timeout 240;
degr-wfc-timeout 120;
become-primary-on backuppc;
}
disk {
on-io-error detach;
no-disk-flushes;
no-md-flushes;
use-bmbv;
}
net {
cram-hmac-alg "sha1";
shared-secret "ixxxxxxxxxxxxxxi";
ping-timeout 100;
}
# syncer { rate 5M; }
on backuppc {
device /dev/drbd0;
disk /dev/vg1/backuppc;
address 192.168.34.1:7789;
meta-disk internal;
}
on drbd {
device /dev/drbd0;
disk /dev/sda;
address 192.168.34.16:7789;
meta-disk internal;
}
}
All hints are welcom!
Thanks
/Christian
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