Cluster Network Activity
Posted on 2013-12-06
I have a 4 Node Cluster using Hyper V and 2008 server. There are two SAN Storage servers. I opened my taskmanger and put it on the network traffic. I logged into each node. I copied a 7GB VM onto the desktop. I did this from each node. All 4 nodes have 2 two iSCSI connections via gigabit network connecting to the san using MPIO. San Has 4 iscsi ports.
On each node I could see the VM copied at about 110mbs and averaged 47% activity on each iSCSI connection.
1. Is that normal? When i only use one Nic it averages 97% and the same 110mbs. Wouldn't two nics be faster.
Why am not getting 200 mbs?
NOW THE WEIRDNESS
I reversed the test. This time I copied the same VM from each desktop back to the SAN from which it came. I started with Node 1. I had only HEARTBEAT activity and no iSCSI activity on Node 1. When I looked at Node 4, it had a ton of HEARTBEAT activity and the two iscsi ports lit up and they seem to be doing the work.
1. Why is this happening? I thought the heartbeat was for live migration only. Why didn't node 1 iSCSI ports copy the VM from its own desktop straight to the san. Why did it take the VM from its desktop send it to node 4 through the heartbeat nic to where node 4 used it's iSCSI port to copy it back to the SAN?
Also i noticed heartbeats were at 92% activity but iscsi again was split 50/50.
This time my HEARTBEAT Nic had all the activity and there was no iscsi traffic.