Comments on: Essential Reading for VMware ESX iSCSI Users!

By: Critical Thinking

Critical Thinking — Mon, 03 Oct 2011 18:08:00 +0000

“The most common configuration (ESX software iSCSI) is limited to about 160 MB/s per iSCSI target over one-gigabit Ethernet”
…What??? I think not. One Gbps equals 1,073,741,824 BITs, not BYTEs. MB/s is the abbreviation for MegaBYTEs per second. If you take 1,073,741,824/8 you get 134,217,728 Bytes, or other words 128MB/s. However, there is IP over head, iSCSI over head, etc. The best real world performance you might hope for is 90 MB/s, and that’s assuming everything is completely optimal. There is not a snow balls chance in hell you are ever going to see 160MB/s, or anything close, over a 1000 Base-T link, period.

Now if you want to say he meant 160Mb/s, I would hope that was wrong, as 160Mb/s is only 20MB/s, which is SUPER slow. Though that is certainly in the neighborhood of the performance I’m seeing, so that might be the case. But I would have to wonder why it would only be able to saturate 22% of the available bandwidth over a dedicated gigabit connection. (Running direct cable from ESXi to Solaris ZFS.)

By: san

san — Thu, 02 Dec 2010 13:30:00 +0000

A step-by-step guide for configuring HA iSCSI SAN with CDP for vmware ESX/ ESXi Server.
http://www.kernsafe.com/article_product.aspx?id=5&aid=49

By: webroalty

webroalty — Thu, 07 Jan 2010 22:30:55 +0000

Very good posting. I just love it.
Good luck man with your work.

http://webroyalty.com

By: sfoskett

sfoskett — Mon, 05 Oct 2009 19:31:44 +0000

Yes, the folks have put together an updated post! See it here:
http://blogs.netapp.com/virtualstorageguy/2009/...

By: sfoskett

sfoskett — Mon, 05 Oct 2009 15:31:44 +0000

Yes, the folks have put together an updated post! See it here:
http://blogs.netapp.com/virtualstorageguy/2009/...

By: David

David — Sun, 04 Oct 2009 02:15:12 +0000

Has anything changed about this since vsphere was released or is this article still up to date?

By: Raymond Brighenti

Raymond Brighenti — Wed, 04 Feb 2009 19:34:01 +0000

Can anyone verify this comment from Equallogic? I don't remember seeing anywhere that you'll get performance problems by having a stanby NIC… strange

Please Note: To avoid severe performance degradation, please use the IP or MAC hash option with Multiple Physical trunked/channel group (non-stacked) switches. Having any „stand-by‟ physical NICs in your vSwitch can also result in severe performance degradation.

By: Raymond Brighenti

Raymond Brighenti — Wed, 04 Feb 2009 16:34:01 +0000

Can anyone verify this comment from Equallogic? I don't remember seeing anywhere that you'll get performance problems by having a stanby NIC… strange

By: Chad Sakac

Chad Sakac — Tue, 27 Jan 2009 12:55:53 +0000

Thanks Steve – it was hard to make it multivendor, and involved some compromises – but nothing fatal, and I think the compromises were right to make it multi-vendor.

Two corrections (I'm being an nit/engineer about this
- the 4th bullet is the key one.
- on link aggr , I think you've distilled it a bit too far… it can help, just less than people would naturally expect…. You still need to use something to ensure outbound use of multiple links (something I don't think we did well enough in the post – for a followup) – this is either via link aggregation (but you still need multiple iSCSI targets, and likely will also use MPIO config)