I don't think it's the raid code I've dropped the disk out of the
array and I still cannot get anymore that 4MB/sec out of it...

[jeff@nas ~]$dd if=/dev/zero of=/mnt/sdj/bonnie/test.tmp bs=4k
count=2000000 && sync && dd if=/dev/zero of=/mnt/sdd/bonnie/test.tmp
bs=4k count=2000000 && sync

2000000+0 records in
2000000+0 records out
8192000000 bytes (8.2 GB) copied, 231.778 s, 35.3 MB/s <-- WD Green
RMA I got back yesterday.

2000000+0 records in
2000000+0 records out
8192000000 bytes (8.2 GB) copied, 1818.18 s, 4.5 MB/s <-- Dud one.

Perhaps it's time to RMA the RMA.

On 21 March 2014 04:46, Bernd Schubert
[off-list ref] wrote:

On 03/20/2014 02:12 AM, Jeff Allison wrote:

quoted

The gist of my question is what kind of resync speed should I expect?

I have a HP N54L Microserver running centos 6.5.

In this box I have a 3x2TB disk raid 5 array, which I am in the
process of extending to a 4x2TB raid 5 array.

I've added the new disk --> mdadm --add /dev/md0 /dev/sdb

And grown the array --> mdadm --grow /dev/md0 --raid-devices=4

Now the problem the resync speed is v slow, it refuses to rise above
5MB, in general it sits at 4M.

Per second?

quoted

from looking at glances it would appear that writing to the new disk
is the bottle neck, /dev/sdb is the new disk.

Disk I/O In/s Out/s
md0 0 0
sda1 0 0
sda2 0 1K
sdb1 3.92M 0
sdc1 24.2M 54.7M
sdd1 11.2M 54.7M
sde1 16.3M 54.7M

Could you please send output of 'iostat -xm 1'? Also, do you anything in
'top' that takes 100% CPU?

Thanks,
Bernd