VM's slow on iscsi san

[dwilli]

I have an HP MSA1510i ISCSI SAN with a shelf full of 300gb 15k drives that is divided into 2 luns of 7 drives each in a RAID5 array. They are connected to my cluster of 4 hosts running 3.5 u2. While applying the latyest patch I moved most of my systems to the SAN storage across the 2 luns. I am seeing very poor performance on the VM's that are not on local storage anymore. Before I go back to local storage are there any suggestions for getting better performance from my SAN?

[weinstein5]

I guess the key question is what does iSCSI network look like? Is it isolated and only carrying iSCSI traffic? How many NICs do you have in your host being utilized for iSCSI? How many NICs do you have in the MSA?

[wpatton]

"very poor performance" - What are we talking about here? Do you have metrics for performance pre and post migration to the iSCSI SAN?

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[dwilli]

The iSCSI network is isolated and has its own switch. I currently only have one NIC from the host to the SAN but have more NIC's available if needed. I need to check the NIC in the MSA, I think 2.

[dwilli]

The quick take on performance is how long it takes for a VM to start. I have a few 2008 servers that on the SAN take more than 5 minutes to start and have the VMtools running. When moved to local storage on the host it takes under 1 minute for the same systems to start. Also i had a business unit report an increase in lag for an app they are running on a VM that was moved to the SAN last night. They were used to seeing a 3-5 second delay on the process, it now exceeds 20 seconds.

[wpatton]

Have you checked the disk performance via the Virtual Infrastructure Client or Virtual Center? One connected 1gbps nic, I assume it is 1gbps, might not be enough bandwidth for the amount of vms you are running.

Also, are you running Jumbo Frames with software iSCSI initiators? If so, turning off jumbo frames may greatly increase your performance as well.

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[dwilli]

I iwll check the performance. I am not sure about the jumbo frame. Any suggestions on how I verify that?

[dwilli]

A few changes have been made. I created a network switch just for VMotion, i had it enabled on the SAN switch and this is not recommended. Second, it turns out that the HP MSA1510i iSCSI SAN is supported with a single active controller. HP released a firmware update for this unit to be compatible with ESX3.5 that makes both controllers active, when they used to be active/passive. I am working on disabling the second controller. HP said the connections would failover to the existing controller when I disabled the other, but that was not the case.

[BUGCHK]

Watch out - you could convert your MSA1510i into a doorstop:

http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1259421