Migration from local datastore to NFS datastore fast, NFS to local is slow

[Godric7000]

I have an ESXi v4.0 Update 1 server and an Openfiler 2.3 SAN doing NFS. Hardware is a Cisco UCS C-200 M1. I've noticed that if I do a cold storage vMotion from the ESXi host to the NFS datastore, I get around 300Mbps on the switchport and an approximate 7G OS took about 6-7 minutes to move. If I go to move that SAME VM back to local storage, it takes like 30-35 minutes! Odd thing is that if I look at the switch ports, ill see it doing around 60-70Mbps at some times, other times the transfer is doing 900-980Mbp.

I have a dedicated vmnic on the ESXi server to communicate with the SAN via NFS. The main purpose of the SAN is simply for storage of ISO's and Templates. Both the ESXi server and Openfiler are running at Gig and are plugged into a Cisco 3560 switch on Gig interfaces. Jumbo frames are not enabled as of yet. Both the Openprofiler server and the ESXi interface sit on a VLAN of their own.

Does anyone know why I would have such a drastic difference in times to do the migration?? It confuses me why it would be transferring at 60-70Mbps part of the time and then all the sudden crank up to full Gig speeds.

Thanks!

[AntonVZhbankov]

Do you have battery installed for local RAID?

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[Godric7000]

For now, I don't have the 2 local 500G drives using RAID b/c the server shipped w/o a hardware based RAID card. The server only has software RAID which isn't going to work with ESXi. I have a hard time thinking it has anything to do with RAID though because I actually get 900-980Mbps when migrating the VM from the SAN to the local drives. Its just not consistent. I will do 60Mbps for a bit then kick into overdrive and do the 1Gbps speeds and then other times throughout the migration there is really nothing going on. If I browse to the datastore through vCenter, I'll see a little over 3 gig transferred but then it just kinda hangs. If I keep hitting refresh, the file size doesn't increase until all the sudden there is another burst of data where I get a full 1Gbps.....

[BruceMcMillan]

What version of the C200 BIOS are you running? There was a new version that was released in the April / May timeframe.

It might also be worth looking at the IOS version of the switch.

[Godric7000]

C200.1.1.1a.0 (Build Date: 03/29/2010)

Thats the latest BIOS...

Its unlikely to be the IOS on the switch...only time I ran into issues like that were on 3750's with QoS which ended up being a bug. Its just very odd that the total time to migrate from NFS to local is so much longer than local to NFS yet when the NFS to local gets going, it transfers at near gigabit speeds. The rest of the time its just sitting there transferring at around 50-60Mbps

[BruceMcMillan]

Have you tried getting a baseline with Iometer? That might help tell you if the issue is network-related or disk-related.