A Small Step For VMware, A Giant Leap For iSCSI

On July 13, VMware announced the introduction of vSphere 4.1 to "advance the foundation for cloud computing." Advancing the foundation of cloud computing is then broken down into five sets of enhancements.  Within the category of enhancements called "increased performance through open integration with storage environments," lies a diamond in the rough. It's where you find that vSphere 4.1 enables 10Gb iSCSI hardware offload.

Before VMware supported 10Gb iSCSI offload, data center managers connected their VMware servers to 10Gb iSCSI SANs using a combination of NIC hardware and fat iSCSI device drivers, a configuration where most of the iSCSI protocol processing is done by the VMware server. Now with vSphere 4.1, VMware supports the latest generation of converged NICs (C-NC) that use thin iSCSI drivers, a scenario where most of the iSCSI protocol processing is done by the iSCSI offload engine in the C-NIC.

iSCSI HBA offload boosts the performance of 10Gb C-NICs in terms of IOPs per GHz of CPU resource, or CPU efficiency. According to Page Tagizad, product line ddirector for Broadcom High Speed Controllers, "Broadcom 10Gb C-NICs  with iSCSI HBA offload deliver nearly 2X higher CPU efficiency when compared to NICs without iSCSI HBA offload."

The result is, as of July 13, 10Gb iSCSI storage deployed with VMware uses a lot less of the precious CPU resources that rightfully belong to virtual machines and business applications. This may be a small step for VMware, but it's a giant leap for data center managers and vendors that have a stake in using VMware and iSCSI storage together.

The biggest beneficiaries of VMware's new support for iSCSI offload are data center managers using iSCSI storage. Always striving to increase the density of their compute nodes in order to save money and simplify management, VMware just awarded these data center managers free server resources they can use to create a little performance headroom or to support more application loads.

Dell, EMC, HP and IBM also benefit from VMware's new support for iSCSI offload. Each of these leading storage vendors are experiencing growth in the mid-market with iSCSI storage and are knocking on the door of large data centers with enterprise-class 10Gb iSCSI solutions. VMware support for iSCSI offload means the new class of massive 10Gb iSCSI storage systems won't bury enterprise servers with iSCSI protocol processing that should be done by C-NICs. Storage protocol processing offload is a requirement for enterprise-class SAN deployments and iSCSI offload will help the leading storage vendors design iSCSI storage into large virtualized data centers.

Another big beneficiary of VMware's latest announcement is Broadcom. The company's 957711 10GbE C-NICs have the only iSCSI offload engines certified by VMware today. That means until other iSCSI offload engines are certified, Compellent, Dell, EMC, HP and IBM, and other storage vendors are likely to recommend Broadcom C-NICs when they're designing iSCSI SANs for vSphere 4.1 environments.

Just as IT organizations wouldn't think of deploying Fibre Channel SANs and expect their VMware servers to do Fibre Channel protocol processing, they never should have to deploy iSCSI SANs with their VMware servers wasting cycles on iSCSI protocol processing.  That work has always been done by Fibre Channel HBAs and can now be done by 10Gb C-NICs. With vSphere 4.1, a new best practice has been established for server virtualization and iSCSI storage: iSCSI offload must be enabled.