[DRBD-user] Diagnosing DRBD Slowness

Robinson, Eric eric.robinson at psmnv.com
Tue Oct 21 22:15:39 CEST 2008

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


> common {
>    syncer {
>     rate 33M;
>     al-extents 257;
>   }
> }

>This will restrict your sync to 33MB/sec, despite ability of disk.

True, but the sync speed I'm seeing is only about 300K per second, so I
didn't think raising the syncer limit would make any difference. 


> Try changing to limit of network card (on both servers) and enter:

> # drbdadm adjust

> Does this fix your problem?

By golly, I think it did. It now shows 37MB/sec instead of 300K/sec and
the average is steadily rising.

[root at ha03 download]# cat /proc/drbd
version: 8.0.13 (api:86/proto:86)
GIT-hash: ee3ad77563d2e87171a3da17cc002ddfd1677dbe build by
buildsvn at c5-i386-build, 2008-08-07 13:42:56
 0: cs:Connected st:Primary/Secondary ds:UpToDate/UpToDate C r---
    ns:196 nr:0 dw:196 dr:572 al:4 bm:1 lo:0 pe:0 ua:0 ap:0
        resync: used:0/61 hits:9 misses:1 starving:0 dirty:0 changed:1
        act_log: used:0/257 hits:45 misses:4 starving:0 dirty:0
changed:4
 1: cs:SyncSource st:Primary/Secondary ds:UpToDate/Inconsistent C r---
    ns:118430388 nr:0 dw:0 dr:118430944 al:0 bm:7228 lo:0 pe:13 ua:18
ap:0
        [==>.................] sync'ed: 18.3% (519206/634860)M
        finish: 3:59:29 speed: 36,932 (420) K/sec
        resync: used:1/61 hits:7394675 misses:7229 starving:0 dirty:0
changed:7229
        act_log: used:0/257 hits:0 misses:0 starving:0 dirty:0 changed:0


That's weird because this is the second resource in the system. The
first one sync'd OK. Does that make any sense?







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