Essential Reading for VMware ESX iSCSI Users!

If you use or are interested in VMware ESX 3.x and iSCSI, you simply must go read  Chad Sakac’s post on the topic. Co-written with just about everyone in the industry (including EMC, VMware, NetApp, Dell/EqualLogic, and HP/Lefthand), Chad has put together a “cheat sheet” on the ins and outs of iSCSI connectivity and performance in ESX 3.x.

Top takeaways (and I’ve been preaching about these for a while myself, too!)

  • Ethernet link aggregation doesn’t buy you anything in iSCSI environments
  • iSCSI HBA’s don’t buy you much other than boot-from-SAN in ESX, either
  • The most common configuration (ESX software iSCSI) is limited to about 160 MB/s per iSCSI target over one-gigabit Ethernet, but that’s probably fine for most applications
  • Adding multiple iSCSI targets adds performance across the board, but configurations vary by array
  • Maximum per-target performance comes from guest-side software iSCSI, which can make use of multiple Ethernet links to push each array as fast as it can go

Thanks for putting together such a great article, guys!

About the author

Stephen Foskett

Stephen Foskett is an active participant in the world of enterprise information technology, currently focusing on enterprise storage, server virtualization, networking, and cloud computing. He organizes the popular Tech Field Day event series for Gestalt IT and runs Foskett Services. A long-time voice in the storage industry, Stephen has authored numerous articles for industry publications, and is a popular presenter at industry events. He can be found online at,, and on Twitter at @SFoskett.

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