[DRBD-user] Performance problem on drbd8 2-node cluster

Gianni Milo gianni.milo22 at gmail.com
Mon May 6 13:20:38 CEST 2019

I would do same tests on the backing storage first, without drbd, cluster
management or any other complexity involved. Then after confirming that
there's no any kind of bottleneck there, I would slowly move to the "upper
layers" ...

On Mon, 6 May 2019 at 09:49, Marco Marino <marino.mrc at gmail.com> wrote:

> Hello, I'm using drbd 8.4.11 on a two node cluster on top of centos 7.
> Both servers have the same hardware configuration: same cpu, ram,
> disks,...More precisely there is a Megaraid lsi SAS 9361-8i with a raid5
> volume. CacheCade is enabled for both controllers and I have a raid0 volume
> with 4x256GB SSD disks.
> I'm trying to do same test with fio:
> fio --filename=/dev/mapper/vg1-vol2 --direct=1 --rw=randrw
> --refill_buffers --norandommap --randrepeat=0 --ioengine=libaio --bs=16k
> --rwmixread=30 --iodepth=32 --numjobs=32 --runtime=60 --group_reporting
> --name=16k7030test
> On node 1 I have:
> Run status group 0 (all jobs):
>    READ: bw=259MiB/s (272MB/s), 259MiB/s-259MiB/s (272MB/s-272MB/s),
> io=15.2GiB (16.3GB), run=60021-60021msec
>   WRITE: bw=605MiB/s (635MB/s), 605MiB/s-605MiB/s (635MB/s-635MB/s),
> io=35.5GiB (38.1GB), run=60021-60021msec
> I'm doing the test after this command:
> pcs cluster standby  --> on node 2. So, there are no write through the
> replication network and I can test the effective speed of the disk
> if I try to do the same thing from node2 I have a degraded performance:
> Run status group 0 (all jobs):
>    READ: bw=101MiB/s (105MB/s), 101MiB/s-101MiB/s (105MB/s-105MB/s),
> io=6039MiB (6332MB), run=60068-60068msec
>   WRITE: bw=234MiB/s (245MB/s), 234MiB/s-234MiB/s (245MB/s-245MB/s),
> io=13.7GiB (14.7GB), run=60068-60068msec
> Someone can give me an advice? Why this happens? I repeat: there is the
> same configuration on both servers. I can check any parameter and I can
> give more details if needed.
> Thank you
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> drbd-user at lists.linbit.com
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