Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
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 at 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
>
>
>
> _______________________________________________
> drbd-user mailing list
> drbd-user at lists.linbit.com
> http://lists.linbit.com/mailman/listinfo/drbd-user
>