[DRBD-user] [Q] What is causing drbd to be slow and cycle between a little fast and very slow?

Lars Ellenberg Lars.Ellenberg at linbit.com
Mon Feb 20 10:09:02 CET 2006

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


/ 2006-02-19 22:02:08 -0500
\ Maurice Volaski:
> I'm seeing the "problem" again. This time secondary is doing a partial sync to
> the primary.
> 
>  1: cs:SyncTarget st:Secondary/Primary ld:Inconsistent
>     ns:0 nr:558860 dw:558860 dr:0 al:0 bm:994 lo:1 pe:0 ua:0 ap:0
>         [=================>..] sync'ed: 89.7% (68540/627400)K
>         finish: 0:15:42 speed: 48 (2,972) K/sec
> 
>  2: cs:Connected st:Secondary/Primary ld:Consistent
>     ns:0 nr:536140 dw:536140 dr:0 al:0 bm:814 lo:0 pe:0 ua:0 ap:0
>  3: cs:SyncTarget st:Secondary/Primary ld:Inconsistent
>     ns:0 nr:975720 dw:975720 dr:0 al:0 bm:494 lo:1 pe:0 ua:0 ap:0
>         [============>.......] sync'ed: 61.4% (621876/1597596)K
>         finish: 0:01:39 speed: 6,232 (5,188) K/sec
>  4: cs:SyncTarget st:Secondary/Primary ld:Inconsistent
>     ns:0 nr:970908 dw:970908 dr:0 al:0 bm:335 lo:1 pe:0 ua:0 ap:0
>         [==============>.....] sync'ed: 70.9% (401564/1372472)K
>         finish: 0:00:41 speed: 9,644 (5,164) K/sec
>  5: cs:Connected st:Secondary/Primary ld:Consistent
>     ns:0 nr:608476 dw:608476 dr:0 al:0 bm:687 lo:0 pe:0 ua:0 ap:0
>  6: cs:SyncTarget st:Secondary/Primary ld:Inconsistent
>     ns:0 nr:268732 dw:268732 dr:0 al:0 bm:1875 lo:1 pe:0 ua:0 ap:0
>         [==========>.........] sync'ed: 50.4% (267664/536396)K
>         finish: 0:00:39 speed: 6,724 (1,428) K/sec
> 
>  7: cs:SyncTarget st:Secondary/Primary ld:Inconsistent
>     ns:0 nr:525212 dw:525212 dr:0 al:0 bm:1071 lo:19 pe:0 ua:19 ap:0
>         [===================>] sync'ed:100.0% (3944/529080)K
>         finish: 0:00:19 speed: 72 (2,792) K/sec
> 
>  8: cs:SyncTarget st:Secondary/Primary ld:Inconsistent
>     ns:0 nr:750064 dw:750064 dr:0 al:0 bm:775 lo:805 pe:0 ua:804 ap:0
>         [=====>..............] sync'ed: 27.8% (1969268/2716116)K
>         finish: 0:03:06 speed: 10,536 (3,972) K/sec
> Note the low values for 1 and 7. I'm not sure the actual throughput is this
> low. It appears to be just an artifact of how the values are being calculated.

as it seems, all your resources are syncing at the same time, thus
sharing the io and network bandwidth, the interupts and whatever
callbacks and other resources are neccessary to process it.

what we see here is in sum ~33 MegaByte/second.
Maybe thats just it for your setup.
You could use the "sync-group" parameter, to serialize resync.

besides, you are right, the values are guestimates only.

grep in syslog for "Resync done (total" to get the "real" figures.

-- 
: Lars Ellenberg                                  Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH            Fax +43-1-8178292-82 :
: Schoenbrunner Str. 244, A-1120 Vienna/Europe   http://www.linbit.com :
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