Fredrik Lindgren [off-list ref] wrote:

Hello,

On 02/07/2013 01:37 PM, Adam Goryachev wrote:

quoted

On 07/02/13 23:01, Brad Campbell wrote:

quoted

On 07/02/13 18:19, Adam Goryachev wrote:

BTW, I just created a small LV (15G) and ran a couple of write tests
(well, not proper one, but at least you get some idea how bad things

are).

quoted

dd if=/dev/zero of=/dev/vg0/testlv oflag=direct bs=16k count=50k
^C50695+0 records in
50695+0 records out
830586880 bytes (831 MB) copied, 99.4635 s, 8.4 MB/s

From the iostat output it seems quite clear that the culprit is the
drbd2 device. The /dev/sd[b-f] seems to have plenty more to give,
even though they're doing some 1400 iops each (which seems a
lot for the throughput you're seeing, why are the IOs towards the
physical disks so small?).

Regarding that drbd device, Is there some mirroring being done to
another machine by way of drbd? If so, with a sync-mirror to another
machine over the network 8,4Mb/s could be quite "normal", right?

Thank you for the smack, I realise now that I was stupidly doing this late at night, and as you suggested, the secondary comes online after business hours. I will need to redo my test after manually disconnecting the secondary server after hours.

Please ignore the above data, I will re-test tonight and advise.

Regards,
Adam

--
Adam Goryachev
Website Managers
www.websitemanagers.com.au