Block alignment is an important topic that is often overlooked in storage. I read a blog entry by Robin Harris a couple months back about the importance of block alignment with the new 4KB  drives. I was curious to test the theory on one of the new 4KB drives, but I did not have one on hand. That got me thinking about Solid State Disk (SSD) devices. If filesystem misalignment hurts traditional spinning disk performance, how would it impact SSD performance. In short, it is ugly.

Here is a chart showing the difference between aligned and misaligned random read operations to a Sun F20 card. I guess it is officially an Oracle F20 card. Read more…

I spoke at TechForum in New York earlier this week. Here is a copy of my presentation for anyone who is interested. The official title is “Rethinking Storage Strategies: How Virtualization is Transforming Storage.” At a high level, I spoke about the current trends in storage and how they play together with server virtualization. I do not think it will have the same impact without the running commentary, so feel free to comment here or drop me a line if you have any questions.

  Storage Trends and Server Virtualization (199.0 KiB)

Project Crossbow is an innovate, and I think important, new contribution to the OpenSolaris project. Crossbow makes network virtualization and resource management first-class citizens in OpenSolaris. If follows in the footsteps of ZFS by having a simple and easy-to-understand interface, while providing great flexibility and power to the administrator. Crossbow can only be found in OpenSolaris, and is not available in Solaris 10. My February column for ;login: Magazine describes and explores Project Crossbow in detail. You can download it here, but as always I encourage you to become a member of Usenix, thereby gaining access to all of the content of ;login: (along with many other great benefits).

  2010-02-galvin.pdf (678.9 KiB)

I have received a few questions relating to my previous post about NetApp VMware bootstorm results and want to answer them here.  I have also had a chance to look through the performance data gathered during the tests and have a few interesting data points to share. I also wanted to mention that I now have a pair of second generation Performance Accelerator Modules (PAM 2) in hand and will be publishing updated VMware boot storm results with the larger capacity cards.

What type of disk were the virtual machines stored on?

• The virtual machines were stored on a SATA RAID-DP aggregate.

What was the rate of data reduction through deduplication?

• The VMDK files were all fully provisioned at the time of creation. Each operating system type was placed on a different NFS datastore. This resulted in 50 virtual machines on each of 4 shares. The deduplication reduced the physical footprint of the data by 97%

A few interesting stats gathered during the testing. These numbers are not exact and due to the somewhat imprecise nature of starting and stopping statit in synchronization with the start and end of each test.

• The CPU utilization moved inversely with the boot time. The shorter the boot time, the higher the CPU utilization. This is not surprising as during the faster boots, the CPUs were not waiting around for disk drives to respond. More data was served from cache the the CPU could stay more utilized.
• The total NFS operations required for each test was 2.8 million.
• The total GB read by the VMware physical servers from the NetApp was roughly 49GB.
• The total GB read from disk trended down between cold and warm cache boots. This is what I expected and would be somewhat concerned if it was not true.
• The total GB read from disk trended down with the addition of each PAM. Again, I would be somewhat concerned if this was not the case.
• The total GB read from disk took a significant drop when the data was deduplicated. This helps to prove out the theory that NetApp is no longer going to disk for every read of a different logical block that points to the same physical block.

How much disk load was eliminated by the combination of dedup and PAM?

• The cold boots with no dedup and no PAM read about 67GB of data from disk. The cold boot with dedup and no PAM dropped that down to around 16GB. Adding 2 PAM (or 32GB of extended dedup aware cache) dropped the amount of data read from disk to less that 4GB.

There is still time to register for the  VMware vs. Hyper-V Hands-on Workshop we are holding on Wednesday, November 18th, at the Hilton Boston/Woburn hotel in Woburn, MA.

The workshop will begin at 8:30 am and includes lunch. During the workshop John Laferriere will present a quick overview of Corporate Technologies. Next I will present a talk based on our VMware vSphere 4 vs. Hyper-V R2 white paper. Next Sean Daly and Joe Gries will do hands-on demonstrations of the two technologies. This will be followed by Q&A and lunch.

We are encouraging attendees to ask us about specific use cases and solution requirements to optimize the value of the workshop.  For more details and to register please see the invitation.

There are many, many choices available when it comes to virtualization technologies. Even within server virtualization, there are many options. Once the choices have been narrowed, it is still a chore to wade through the options and limitations to determine the best fit for a given datacenter environment.

Some frequent decision points include:

• Is your environment large enough to bother virtualizing?
• If you are running VMware, should you consider Microsoft Windows Server 2008 Hyper-V R2?
• Can Hyper-V run other guest operating systems?
• What should a Windows-only shop do?

To help ease the effort, we’ve created a decision flow chart involving the two contenders on the short list at most sites – VMware vSphere 4 and Microsoft Hyper-V R2. This chart starts from your current infrastructure and leads you through the important decisions, and to the conclusions you are likely to reach.

The chart is based on much more detailed information provided in our vSphere vs. Hyper-V whitepaper available for download in this blog posting as well as the associated talk available here.

Hopefully this chart will help you make your server virtualization decisions. Please get in touch if you would like to review the whitepaper or have us evaluate the virtualization options for your datacenter. (Please click on the image for a full-size view.)

We’ve just announced the next NEOSUG (New England Open Solaris User’s Group) meeting

You Are Invited to the New England Open Solaris Users Group

Topic: All Virtualization all the Time

When: October 6th, 2009 6:00PM to 9:00 PM

Where: Sun Microsystems Burlington Campus; 1 Network Drive, Burlington, MA

RSVP: To Linda Wendlandt: lwendlandt at cptech dot com lwendlandt@cptech.com

Registration Required! – so we can plan food and drink

Join Eric Sharakan, Kais Belgaied, and Peter Galvin in an update on LDOMs, Solaris on Xen, project Crossbow (network virtualization), and Solaris Containers.

AGENDA:

6:00-6:20: Registration, Pizza and Beverages

6:20-6:30: Introductions: Peter Galvin, CTO, Corporate Technologies

6:30-7:30: Presentation: Logical Domains & Solaris on Xen – Eric Sharakan, Senior Staff Engineer, Sun Microsystems

7:30-8:00: Presentation: Crossbow – Kais Belgaied, Senior Staff Engineer, Sun Microsystems

8:00-8:30: Presentation: Solaris containers – Peter Galvin, CTO – IT Architecture, Corporate Technologies

**** Also we’ll be giving out official NEOSUG T-Shirts and other trinkets, and copies of the OpenSolaris CD and instruction manual.

For more details on the talks please visit the NEOSUG web site at http://www.opensolaris.org/os/project/ne-osug/

We’re pleased to make available our first whitepaper. This one is a technical analysis of  vSphere 4 vs. Hyper-V R2. If you have any comments, please post them here.

The Executive Summary should give you guidance as to whether this whitepaper will be of use to you:

The battle to be your virtualization vendor is in full swing, and it has important ramifications for the vendors involved, and for your data center. The goal of this whitepaper is to analyze the technical aspects of the two major choices: VMware vSphere 4 and Microsoft Hyper-V R2 (as part of Windows Server 2008 R2). This paper considers server virtualization alone, not desktop virtualization or “presentation virtualization”. Certainly presentation virtualization will be an important aspect of the virtualization gamut, but with the entry of Microsoft into the server virtualization market, and the still-unrealized huge potential for server virtualization, this is a topic of great interest to many datacenters.

This whitepaper covers the following topics:
› A summary of virtualization technologies and terms.
› The reasons to consider virtualizing.
› The features of virtualization and the effect it has on application implementation, and datacenter facility implementation and management.
› The impact that future server technology will have in driving virtualization, based on the need of datacenters to achieve optimal resource use and optimal application performance.
› Decision criteria to use in determining when and how to virtualize a datacenter.
› A description and comparison of the features and pricing of vSphere and Hyper-V.
› An analysis of the current state of virtualization and best practices to consider when deploying virtualized infrastructure.
› Our prognosis of the future of virtualization, the expected next feature sets of virtualization, and the future of data centers management and application deployment.
› Advice on how to determine which of the virtualization offerings to consider and how to test that chosen path.
› Reference pointers and suggestions for further reading.

The whitepaper is free and available for download in .pdf format. Registration is not required, but if you register, we will let you know when the next whitepaper comes out. We have a simple privacy policy and we will not fill your inbox with junk.

  Virtualization Whitepaper - VMware vSphere vs. Microsoft Hyper-V (1.1 MiB)

My April 2009 column has been published in ;login: Magazine. This month it’s The Sun Virtualization Guide- making sense of and decisions about the various Sun virtualization options. LDOMs, Containers, Domains and Xen are all options worth considering, and this guide leads you through what each does and when to use them. Some ;login: contents is freely available at ;login:, but my column this month is not one of them. I’ve posted the .pdf here for those without a USENIX membership (although I strongly recommend you get one if you are interested in all things Unix).

Sometimes I think the only people who read technology blogs are people who write other technology blogs. I have no way to figure out if this is true or not, but it is an interesting topic to ponder. Do IT end users actually read technology blogs? If they are reading, they do not seem to comment very frequently. Much more often comments come from other bloggers or competing vendors.

That said, I am going to talk about an issue that some of the storage bloggers seem to be caught up in at the moment. The issue of ‘emulated FC’ vs ‘real FC.’ Let me start off by sharing a few recent posts from other blogs:

Chuck Hollis at EMC writes about the EMC/Dell relationship and takes the opportunity to compare EMC to NetApp. In this case, he is comparing the EMC NX4 to the NetApp FAS2020. The comment in the post that certainly aggravated NetApp is that EMC does “real deal FC that isn’t emulated.” The obvious implications being that EMC FC is not emulated, NetApp FC is emulated, and FC emulation is bad. (This is not a new debate between EMC and NetApp. Look back through the blogs at both companies and you will find plenty of back and forth on the topic.

Kostadis Russos at NetApp has a post explaining why he, not surprisingly, completely disagrees with Chuck.

Stephen Foskett, a storage consultant, posts what I think is an excellent overview of the issues. He cuts through the marketing spin and asks the right questions. His coverage of the topic is so complete, I almost decided not to write about the topic. I will try not to retrace all the issues he covered. I will hit a couple of his high level points in case you have not had a chance to read his post (I highly recommend it though, it is very good.) In summary:

• All enterprise storage arrays “emulate” Fibre Channel drives to one extent or another
• NetApp is emulating Fibre Channel drives
• All modern storage arrays emulate SCSI drives
• Using the wrong tool for the job will always lead to trouble
• Which is more important to you, integration, performance, or features?

So, why am I writing about it? I am writing about it because Chuck posted a very good blog entry about benchmarking a few days later that, to me, contradicts the importance he gave to ‘real FC’ on 12/9. I have never meet Chuck or Stephen, but they both seem to be very technically adept from their postings.

Without trying to put words in his mouth (text on his blog?), the overall theme of Chuck’s post is to make sure you use meaningful tests if you want meaningful results from a storage product benchmark. He is absolutely correct. I could not agree more. How many times have we seen benchmarks performed that were completely irrelevant to the workload the array would see in production?

Read more…