[DRBD-user] throughput test goes faster on DRBD device than on low level device

Bart Coninckx bart.coninckx at telenet.be
Wed May 26 19:50:36 CEST 2010

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


Yes, identical and yes, indeed 2 gigabit NICs bonded to the other node.

Another resource is active, but not in initial sync.



On Wednesday 26 May 2010 19:28:33 Lee Riemer wrote:
> Are the nodes identical hardware?  I assume you've got at least 2
> Gig-E's worth of bandwidth to the other node.
> 
> Is it replicating to the other node when you test the local device?
> 
> On 5/26/2010 12:24 PM, Bart Coninckx wrote:
> > Hi all,
> >
> > used this benchmark script from the DRBD manual to test one resource:
> >
> > TEST_RESOURCE=test
> > TEST_DEVICE=$(drbdadm sh-dev $TEST_RESOURCE)
> > TEST_LL_DEVICE=$(drbdadm sh-ll-dev $TEST_RESOURCE)
> > drbdadm primary $TEST_RESOURCE
> > for i in $(seq 5); do
> >    dd if=/dev/zero of=$TEST_DEVICE bs=512M count=1 oflag=direct
> > done
> > drbdadm down $TEST_RESOURCE
> > for i in $(seq 5); do
> >    dd if=/dev/zero of=$TEST_LL_DEVICE bs=512M count=1 oflag=direct
> > done
> >
> > results were better for the DRBD device than for the low level device:
> >
> > 1+0 records in
> > 1+0 records out
> > 536870912 bytes (537 MB) copied, 2.04583 seconds, 262 MB/s
> > 1+0 records in
> > 1+0 records out
> > 536870912 bytes (537 MB) copied, 2.25206 seconds, 238 MB/s
> > 1+0 records in
> > 1+0 records out
> > 536870912 bytes (537 MB) copied, 2.7367 seconds, 196 MB/s
> > 1+0 records in
> > 1+0 records out
> > 536870912 bytes (537 MB) copied, 2.67956 seconds, 200 MB/s
> > 1+0 records in
> > 1+0 records out
> > 536870912 bytes (537 MB) copied, 2.67137 seconds, 201 MB/s
> > 1+0 records in
> > 1+0 records out
> > 536870912 bytes (537 MB) copied, 2.76239 seconds, 194 MB/s
> > 1+0 records in
> > 1+0 records out
> > 536870912 bytes (537 MB) copied, 2.72964 seconds, 197 MB/s
> > 1+0 records in
> > 1+0 records out
> > 536870912 bytes (537 MB) copied, 2.7846 seconds, 193 MB/s
> > 1+0 records in
> > 1+0 records out
> > 536870912 bytes (537 MB) copied, 2.77892 seconds, 193 MB/s
> > 1+0 records in
> > 1+0 records out
> > 536870912 bytes (537 MB) copied, 2.75706 seconds, 195 MB/s
> >
> > (first five compared to the last five)
> >
> >
> > How is this possible? I guess I shouldn't complain, but still ...
> >
> > Thx!
> >
> >
> > Bart
> > _______________________________________________
> > drbd-user mailing list
> > drbd-user at lists.linbit.com
> > http://lists.linbit.com/mailman/listinfo/drbd-user
> 
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