Expert Data Labs Blog

We made a huge number of performance improvements in vSphere 4.0. The ESX storage stack was no exception. We ran a wide variety of micro and real world benchmarks to thoroughly evaluate and optimize vSphere’s storage subsystem. It is now even more efficient for the enterprise and ready to support the cloud.

A wide variety of I/O intensive applications will run efficiently on vSphere with all the improvements.  You can find details on the architectural changes and storage performance improvements made in this white paper.

Some of the noteworthy improvements are:

·         VMware Paravirtualized SCSI (PVSCSI driver): vSphere ships with this new high performance virtual storage adapter. Bus logic and LSI logic were the only choices so far. PVSCSI is best suited to run highly I/O intensive applications in the guest more efficiently (reduced CPU cycles) and with increased throughput. This is possible with a series of optimizations explained in the paper.

·         iSCSI support improvements: We made significant improvements in the iSCSI stack for both software and hardware iSCSI. The improvements are not just in terms of performance but features as well. Noteworthy among these is CPU efficiency improvements that range from 7-52% depending on the type and size of I/O.

·         Software iSCSI and NFS support with Jumbo Frames: vSphere adds jumbo frames and 10Gbit NIC networking support for both NFS and iSCSI. This helps drive bandwidth that is many times faster than previous ESX releases.

·         File system improvements for enhanced Virtual Desktop experience and scalable cloud solutions: We made several optimizations in VMware File System (VMFS) with a special focus on enterprise desktop and cloud solutions. File system along with other improvements in different parts of ESX improves performance of several provisioning operations dramatically. An example is “boot storm” performance (where several hundreds of virtual machines are booted simultaneously in a virtual desktop environment). With these improvements time taken to boot a large number of virtual machines simultaneously is many times faster compared to ESX3.5.

ESX supports several different storage protocols like Fibre Channel, iSCSI and NFS. We published a white paper that compares I/O performance using each of these protocols.  Results show that line rate can be achieved with each of the storage protocols for single or multiple virtual machines. The paper also highlights CPU efficiency improvements in vSphere compared to the previous release. This means that more virtual machines can now run on the same hardware.  Graph below shows one example (sequential read, 64KB block size) of the relative CPU cost for each of the storage protocols. Results on ESX 4.0 are shown next to ESX 3.5 to highlight efficiency improvements on all protocols.

Hardware configuration and detailed results can be found in this protocol comparison white paper.