today I did update our iSCSI R3 Enterprise from 2.21 to 5.0 and did create new RAID and a volume with Block I/O. We use the iSCSI storage for our VMWare ESX 3.5 server virtual maschines. Inside a virtual maschine I use IOMeter to measure the disk performance and it was very weak. I was playing with the tuning options (InitialR2t = no, ImmediateData = yes) without performance boost. Now I deleted the Block I/O volume und made a new File I/O volume and get acceptable performance after playing with the tuning options.
With Block I/O I get 22 MB/s read and 5 MB/s write and with File I/O I get 57 MB/s read and 48 MB/s write (IOMeter is set to 100% sequential, 64k, 100% read or 100%write).