[DRBD-user] Why is drbd 0.7.22 slow on Opteron 240 EE?

Lars Ellenberg Lars.Ellenberg at linbit.com
Tue Nov 21 16:51:52 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.


/ 2006-11-21 03:39:01 -0500
\ Maurice Volaski:
> On fresh sync of /dev/drbd2, which is 1.4 TB, I'm seeing an average 20.3 MB per second. When I test with ttcp, I 
> routinely see about 64 MB per second. Write tests with dd if=/dev/zero of=/maurice/bonnie/hello bs=400M count=10 

I suggest you
# wget http://svn.drbd.org/drbd/trunk/benchmark/dm.c
# gcc -O -o dm dm.c

and then to benchmark:
 ./dm -x -a 0 -s 4g -b 20m -m -y -p -o /maurice/bonnie/hello
and go from there.

you can combine this with netcat.

> appear to show a write speed on the secondary of about 160 MB  per second, so it doesn't appear that the secondary 
> has any obvious I/O bottleneck.
> 
> So shouldn't drbd be much faster than it actually is?
> 
> I also notice that the secondary is often unresponsive to command line commands and I see messages in the log of 
> the primary:
> drbd2: [drbd2_worker/9750] sock_sendmsg time expired, ko = 3

seems like your secondary needs a lot of time to process the writes.

-- 
: 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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