Greetings,
We are testing OVM 3.1.1 (patched) using NFS repositories (poolfs, and for the VMs files and DNFS Database files) with PVM OL5U8/UEK domUs and are seeing slow read and write speeds.
Could you please share your NFS read and write numbers and any NFS performance tips & tricks?
ENV:
Intel 2 socket/32 core x86 servers with 4 10G NICS
emc vnx array with lots of SSD drives. The storage is at 10GB/s on the same switch with ovs hosts.
Cisco 10G infrastrucure.
The numbers:
1- File transfer using lftp is poor, eg 4.66MB/s. lftp file transfer should be bound by the slowest link which, in this case, is 15MB/s and we only get 1/3 of that.
2- the network speed between two hosts is almost 3Gbps. the network speed between two guests is almost 2Gbps.
3- The direct dd read speed of host on nfs share is 57MB/s, and the direct dd write speed of host on nfs share is 18MB/s. The direct dd read speed of guest on nfs share is 29MB/s, and the direct dd write speed of guest on nfs share is 16MB/s
4- When we mount an nfs folder on the ovs host and do a dd if=./test.zero of=/dev/null bs=16k, we get 130MBps. When we run the same command on a domU, we I get 9MBps using the same nfs mount, comand, mounting with default options.
We have been tuning the TCP Parameter Settings, tunning helps, but the numbers are still poor.
Other NFS posts:
2389209
10500676
Thank you for your support!
Roddy