StarWind Software

Hi there,

Im currently building/testing an "el cheapo" san for ESXi, and so far, i think the performance is quite ok

This is a test from a VM running Windows Server Enterprise 2008 R2 on an ESXi local datastore, using MS iSCSI initiator




As you can see it`s pretty good.

The problem is, when i use the ESXi initiator, i format the lun as vmfs, then create a vm/disk inside this datastore, i get this.



Read result is totally wrong according to network stats, it's about 25 MB/s



Just terrible, what could be the reason of this massive underperformance?

I have a dedicated gigabit switch for iSCSI traffic, using 9K jumbo frames on switch, nics, vmkernels, vmswitchs,
Target server is a xeon 3040, 8 GB ram, two Gb intel nics for iSCSI (teaming), running Windows Server Enterprise 2008 R2
Initiator (ESXi) is a dual xeon 5506 supermicro, using 1 nic for iSCSI

Search this forum a bit. There are plenty of threads / posts about built-in ESX initiator tuning. Hint: delayed ACK and IOPS settings should be altered to "NO" and "1".

Already tried those recommended settings, still no luck.

Anyway, im testing ESXi 5, ATTO is giving me some good results



But if i check the network status



(vmnic1 is the iSCSI dedicated nic)
it doesn't make too much sense to me

i'll give iometer a try later.

Ok, i got iometer results, at least one.

Iometer read 256K sequential



Also i found one of the target's nic was taking down ther preformance



i'll run some more tests tomorrow.

Moderate ones. But still far below expected. You're putting a wagon in front of your horse in any case. You need to tune TCP/IP stack before building storage cluster and improving iSCSI.