iSCSI traffic limited to 100-150 MB/s?

Asif DaslAsif Dasl Member Posts: 2,116 ■■■■■■■■□□
Hello all!

I am having trouble with the speed of my iSCSI traffic and I'm wondering if anybody can point me in the right direction? OK, so this is my lab:

Left-vSphere Host - vSphere 5.5
Asus Z87-PRO
Intel i7-4770T
32 GB DDR-3
500 GB SSD (Win 7) & 500 GB SSD (vSphere 5.5)
1 Onboard NIC & 2 HP NC364T Quad Port NICs - 9 NICs in total.
1 Distributed Switch (with Management, vMotion, iSCSI Port Binding & FT Logging)

Right-vSphere Host - vSphere 5.5
Same as above.

Server 1 - Domain Controller/iSCSI Target
Asus M4A785-M
AMD Phenom II x6 1075T
6 GB DDR-2
1 TB HDD (Server 2012) & 500 GB SSD (iSCSI Target)
5 NICs in total (1 onboard, 1 Quad Port - individual IPs for multiple iSCSI paths, no NIC teaming here)

Server 2 - vCenter Server 5.5/iSCSI Target
Same as Server 1.

The network switch is a HP v1910-48G - No LACP running.

Now to my problem...

I've got an SSD in the Left-vSphere host and when I create a VM using FreeNAS/Openfiler/Server 2012 - when I test this VM with CrystalDiskMark I get 450-500 MB/s running straight off the SSD. Happy days... no problem here.

But, when I create an iSCSI target on that VM and place another VM inside that newly created iSCSI Target, I only get about 100-150 MB/s going over the network. This is the same drive & datastore which runs at 450-500 MB/s.

I have set up iSCSI multipathing correctly (as shown in this YouTube link - using Round Robin) - and the performance tab shows nicely distributed data across the 9 NICs but just not running close to the top speed of the drive.

And, if I create an iSCSI Target on either the Domain Controller or on the vCenter Server the same thing happens. Why does my performance suck over the network so much? I am running Jumbo frames throughout, multiple GigE NICs and have multiple iSCSI paths. The switch says everything is running under 5% utilisation for everything connected while doing a Storage vMotion.

Any ideas on how to improve performance? What am I doing wrong that these guys are getting 380 MB/s?

Thanks in advance!


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