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Author Archives: Devaki Kulkarni

Storage performance improvements in vSphere 4.0

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:

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). This is
possible with a series of optimizations explained in the paper.

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.

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.

system improvements for enhanced Virtual Desktop experience and scalable cloud
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 such as 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


 (Lower is better)


Figure: Relative CPU cost of 64 KB
sequential reads in a single virtual machine


Improved performance using Shared Folders in Workstation 6.0

It’s nice to see Workstation 6.0 being received well. We continue to focus on performance improvements for this product, not just the major subsystems but every feature we support too.  One of the significant improvements I’d like to draw your attention to is in using Shared Folders. Shared Folders allow sharing files between the guest and the host, or among virtual machines.

We’ve now wired up this feature with the guests’ kernel (page) cache. What this means is that your files in the shared folder will now be cached by the guest kernel for faster reads. Writes are done asynchronously, making them faster as well. The attributes (or metadata) of the files are cached, making browsing through your Shared Folder for all your files much quicker. This support is for Linux guests at the moment. With this integration you can expect improvements in performance up to 40%, depending on the usage.

We’ve always received great feedback on the usefulness of this feature, and we hope you continue to enjoy your experience in using Shared folders even more. We are looking into similar improvements for Windows guests as well.

Happy browsing.

Getting the best performance from Workstation 6.0

It was a proud moment for us when Workstation 6.0 went out the door.
While we continue to provide increasing flexibility in using desktop
machines and laptops, running multiple operating systems, and reducing
hardware costs, we’d like for you to enjoy the best performance you can
get from Workstation 6.0.

On top of all the goodness Workstation 6.0 has to offer, we now have a revised performance document as well. You can find it here.
We’ve tried our best to provide tips not only about things that you
could tune with Workstation and its features, but things you could
tweak on your host operating system and within the guest, and even what
to look out for on the hardware level. The reorganization of the
document makes it easy to find what you need to achieve the best
possible experience.

We also have a dedicated section in the performance document for
those of you who are interested in benchmarking with Workstation 6.0 or
in just understanding the performance you could get with it. This
includes recommendations on several benchmarks that you could use and
how to run them in a controlled environment so that the results are
understood easily.

We hope you find this document useful and that you enjoy your
experience using Workstation 6.0. Please tell us about your experiences!