Hi Nishan,

If your vm is deployed in an isolated network all the traffic goes via VR. So 
please check the rate limiting on the VR.
You may have to increase the rate limit value to get more BW.

Thanks,
Sanjeev

-----Original Message-----
From: Nishan Sanjeewa Gunasekara [mailto:nishan.sanje...@gmail.com] 
Sent: Wednesday, March 05, 2014 10:02 AM
To: users
Subject: Disk IO on Cloudstack VMs

Hi,

I'm running CS 4.2.1 on XenServer 6.2 hosts.

My primary storage is a ZFS file system provided via NFS.

When I do a dd test directly from one of the hosts on the NFS mount I get a 
write speed of about 150MBps

 dd if=/dev/zero of=test.dmp bs=1M conv=fdatasync count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 6.99829 seconds, 150 MB/s

But when I do the same test on a Cloudstack VM running on the same host (root 
disk on the same nfs mount ofcourse) I get a very low write speed.
20MBps.

 dd if=/dev/zero of=test.dmp bs=1M conv=fdatasync count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 44.6171 s, 23.5 MB/s

Any ideas how I can improve this ?

Regards,
Nishan

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