RN3220 / RN4200 Crippling iSCSI Write Performance

To offer an update.

I've now upgraded the firmware to 6.7.2, with no change in performance.

I deleted the array and created a new RAID6 accross all 12 drives using FLEX-RAID instead of X-RAID. I let it write the parity overnight and complete the sync and re-tested The performance was worse.

Next I deleted the RAID6, recreated it as a RAID0, and then repeated. The same problem, with similar dire write performance levels. The increase in the read performance is evident though.

Again, keeping it single path, no-MPIO. During the VHDX copy into the iSCSI target, the NIC is unable to get higher than 700Mbps and the Max value on the NIC graph on the RN3220 shows 74.1M. The average value is about 450Mbps. Sending it the other way caps out at about 800Mbps (I would expect higher, but the test EqualLogic shelf is actually busy in production). There is however a very clear difference in write behaviours between the two.

Sending the VHDX from the EqualLogic to the NetGear is bursting! It'll go 200, 700, 100, 300, 500, 400, 700, 200, 400, 600, 700, 400 and so on. Sending the VHDX back to the EqualLogic is completely stable at 800Mbps within a margin of ~40Kbps. It is as if the RN3220 has filled a buffer and had to back off.

I've also tried it on a hypervisor that does not have Dell HIT installed on it in case the Dell DSM is being "anti-competitive". There was no change.

I've re-confirmed the 9K end to end frame size is working correctly.

Here is an ATTO retest after everything new that I have tried. The NetGear is RAID0 in this, the EqualLogic RAID10.

Also to add to the above list, the iSCSI LUN's are formatted as 64K NTFS

p.s. the EqualLogic was extremely busy when I did this, hence the far lower performance numbers.