I'm working on bringing up a 2012 R2 cluster and doing a basic test.  In this cluster, I have two adapters for iSCSI traffic, one for network traffic, and one for the heartbeat.  Cluster node has all the current updates on it.  Everything is set up correctly as far as I can see.  I'm taking a folder with 1GB of random files in it and copying it from the C: drive of a node to an iSCSI LUN.  If I have the LUN set up as a non-CSV disk, the copy happens about three time faster than if I have it set up as a CSV disk.  All I'm doing is using FCM to change the disk from CSV to non-CSV (right-click, Remove from CSV, right-click, Add to CSV).  I can swap it back and forth and each time the copy process is about three time slower when it's a CSV.  Am I missing something here?  I've been through all the usual stuff with regard to the iSCSI adapters, MPIO, drivers, etc.  But I don't think that would have anything to do with this anyway.  The disk is accessed the same with regard to all that whether it's CSV or not, unless I'm missing something.  Right now, I only have a single node configured in the cluster, so it's definitely not anything to do with the CSV being in redirected mode.

I'm not trying to establish any particular transfer speed, I know file transfers are different than actual workloads and performance tools like iometer when it comes to actual numbers.  But it seems to me like the transfers should be close to the same whether the disk is a CSV or not, since I'm not changing anything else.