ISCSI Tuning from default?

[gskjelstad]

All-

I just installed a new installation of ESX 3.5 using a Dell MD3000i ISCSI SAN, and performance is a bit slow for me. I am used to using some EMC FC SANs, and so I'm wondering if there is some steps that i'm missing for tuning either the appliance, the ESX servers themselves, or perhaps some network tuning.

It's pretty much a default installation, with multi-path for fail over, and so I'm just looking for a bit of guidance on direction. Does anyone have any suggestions on where to look for performance tuning? Also, is there a large noticeable different between the hardware initiators and the software initiators? I have some other boxes, I was thinking about bringing online, but they currently do not have supported hardware initiator cards.

Any information/links/guides/websites anyone could provide would be great. (if the information is for 4.0 that would be excellent as well!, since I'll have to upgrade someday...)

Thanks-

Garrett

[Chuck8773]

How fast was you FC connection? ESX 3.5 can only use a single network link to the iSCSI SAN, Hardware or Software Initiator. So unless you have 10 Gbps network, it will be slower than FC. ESX 4 can multi path multiple link for software iSCSI. This will let you get the same performance on the connection to the SAN. Duncan wrote a great acticle on how to set that up in ESX 4.

http://www.yellow-bricks.com/2009/03/18/iscsi-multipathing-with-esxcliexploring-the-next-version-of-...

Charles Killmer, VCP

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[olegarr]

Garrett,

1. Do you have separate network for your iSCSI traffic? If not I would high recommend to do it. Basically, one (or more) network on ESXs should be for Virtual Machines/SC and etc. and another should be for iSCSI traffic only (you might consider to use it for VMotion also)...

2. Increase jumbo frames to 9000 on both SAN and ESX

3. If you are using Windows, you might want to consider use MS iSCSI initiator inside of VMs...

Of course, it's not all, but I would start from those steps...

Olegarr

[gskjelstad]

I have configured a second VLAN just for the ISCSI traffic alone, i haven't enabled jumbo frames on it yet because I wasn't sure how the extra SW initiators that I might add at a later date would take to that. Is there that big of a difference?

I am using ISCSI as the path for the storage for ESX, as for the Microsoft bit, all the file system storage was just in a separate VMDK, should I have set that up in a separate ISCSI lun?