[DRBD-user] Diagnosing DRBD Slowness

Robinson, Eric eric.robinson at psmnv.com
Tue Oct 21 23:56:50 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.


> maybe you forgot the "adjust" last time you added 
> the syncer rate to the config file? default is, for 
> hysterical reasons: 250 kB/s, which is about what 
> you had seen so far. 


That would explain it. But, to be honest, this is my third
heartbeat+drbd cluster and I have never done an adjust before. True, my
load balancing cluster does very little disk work, but my MySQL database
cluster works blazingly fast. Somehow I escaped having to do the adjust
before.

>	nc -l 10000 > /dev/null &
>	dd if=/dev/zero bs=1M count=100 | nc 127.0.0.1 10000

> should be MUCH faster.

And so it is...

[root at ha03 download]# dd if=/dev/zero bs=1M count=100 | nc 127.0.0.1
10000
100+0 records in
100+0 records out
104857600 bytes (105 MB) copied, 0.686014 seconds, 153 MB/s
[1]+  Done                    nc -l 10000 > /dev/null


All mysteries now solved. Sigh. I can end the day in peace. :-)




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