Wednesday, January 30, 2008

Beware VMWare!

Hot on the heels of the Cisco hyper-mega-switch announcement and Yahoo announcing a reduction in workforce despite increasing profits, comes the nose-dive of VMWare's stock price; losing one-third it's value in a single day. Keeping in mind that Wall Street is capable of either irrational exuberance or irrational pessimism, the events pertaining to Yahoo and VMWare are most likely an expression of the latter. Both companies have solid business plans.

From the performance angle, however, it may also be that the honeymoon period is now over in part because VMWare is a victim of its own success. Not only has all the hype surrounding virtualization and consolidation worn a bit thin these days, but it has also attracted the big guns---Microsoft and Oracle---into the market. And customers are not doubt becoming aware that consolidation doesn't always translate into less MIPS or more greenness. The overheads of virtualization can be very significant. The problem for us performance weenies is knowing what are those overheads in a QUANTITATIVE way. As I've stated before:

All virtualization is about illusions and although it is perfectly reasonable to perpetrate such illusions onto a user, it is entirely unreasonable to propagate those same illusions to the performance analyst.

So, here's an opportunity for VMWare to differentiate itself in the madding crowd of new VMM vendors; focus on providing more whistles and less bells. And you (Dear reader), as John Q. Customer/Analyst, should demand it (even if by proxy). If you don't make the ultimate performance issue known to management, how can they be expected to pressure the vendors?

Monday, January 28, 2008

Cisco Systems: "It's the switch, stupid!"

Today, Cisco Systems (San Jose, California) announced its mother of all switching platforms, the Nexus 7000 Series, aimed at what it calls Data Center 3.0 (analogous to Web 2.0, I presume. I missed Data Center 2.0). Cisco is essentially trying to eliminate the need for separate storage networks, server networks, routing, switching and virtualization, by combining them all into a single unified fabric and managing it through Cisco's new proprietary NX-OS ("nex-os", get it?) operating system.

The Nexus 7000 will deliver up to 15 Tbps of switching capacity in a single chassis, with 512 ports for 10 Gbps ethernet, and eventually it is slated to be delivered with 40 Gbps and 100 Gbps ports. Some of the claimed performance speeds-and-feeds appear rather breathtaking:

  • Copy the entire Wikipedia database in 10 milliseconds.
  • Copy the entire searchable Internet in 7.5 Minutes.
  • Download all 90,000 Netflix movies in 38.4 seconds.
  • Send a high-resolution 2 megapixel photo to everyone on earth in 28 minutes.
  • Add a Web server in 9 seconds rather than 90–180 Days.
  • Transmit the data in all U.S. academic research libraries (estimated at more than 2,000 TB) in 1.07 seconds.

If nothing else does it, the 3 significant digits in the last claim tells you this is marketing-speak (read: calculated using max bandwidth assumptions), so a liberal dusting of sodium chloride is recommended.

The concept of a "data center" is currently undergoing a serious transformation and it will be interesting to see how this kind of mega-switch stacks up against alternative approaches, such Google's Data Center in a Box.

Friday, January 18, 2008

Scalability Law as Queueing Model Proven

It never rains in California, it just pours. Not only have we had a lot of seasonal rain lately but it seems to be the season for proofs. In 2002, I proved that Amdahl's law is equivalent to a special kind of queueing behavior. This particular connection with queueing theory had not been made before. Here's a restatement of that theorem.

Wednesday, January 16, 2008

Sun to Purchase MySQL

This could be good news for Oracle. 8-\

Continuing a string of surprising announcements, Sun Microsystems today said it plans to buy the makers of MySQL open-source database software for almost $1,000,000,000 (I like to see all those zeros). Sun does have a lot of cash burning a hole in its pocket, but it also has a less than stellar track record when it comes to acquisitions.

Monday, January 14, 2008

What to Do with Wobbly Numbers in PDQ

Peter Altvogt (Germany) reported an interesting numerical effect while using the load-dependent server model in Section 6.7.11 of "Analyzing Computer System Performance with Perl::PDQ". The default parameters in are set to N = 15 users and M = 3 maximum processes allowed in the sub-system. The PDQ model calculates the joint probability distribution Pr(j|n) of the queue length at the load-dependent server. For these parameters the mean queue length is 4.50 users.

Saturday, January 12, 2008

Erlang Explained

During the GCaP class, last November, I mentioned to my students that I was working on a more intuitive derivation of the Erlang B and C formulae ( the English wiki link to Erlang-C is wrong) associated with the multi-server or M/M/m queue. This queue is very important because it provides a simple performance model of a multiprocessor or multicore systems, amongst other things. When I say simple here, I mean the queueing model is "simple" relative to the complexities of a real multiprocessor (e.g., it does not include the effects of computational overhead). On the other hand, the mathematics of this particular queueing model is not simple. Not only do we need to resort to using some kind of computational aid to solve it (some people have built careers around finding efficient algorithms), the formulae themselves are completely unintuitive. During that class I thought I was pretty close to changing all that; to the point where I thought I might be in a position to present it before the class finished. I was wrong. It took a little bit longer than a week. :-)

Guerrilla Training Schedule for 2008

The preliminary Guerrilla Training Schedule for 2008 has been posted. The embedded PDF includes a brief slide-show of extracts from the various classes. It also includes hyperlinks to the Course Content pages. Some browsers may render the PDF differently. If you have problems, you might try upgrading to the latest Acrobat Reader. The most significant change is that the GDAT class has now been extended to a full 5 days with the addition of Jim Holtman as an instructor, who is "Mr. Wizard" when it comes to using and explaining how to do statistical data analysis with R (or S-Plus).

Please bear with us while we sort out the situation with the hotels. The Crowne Plaza now has new ownership and is undergoing a complete renovation. They are telling us they will be open again by March, but we have to decide if we need to hedge our bets on that claim. It will get sorted out shortly, but if you are planning on attending a Guerrilla class, please make sure you check the schedule page for the latest information.

Hotsos Oracle Symposium 2008

I've been invited to speak again at the Hotsos Oracle Symposium, March 2-6 in Dallas, Texas. I'm more than happy to do this because I found last year's symposium to be a first class operation with plenty of great speakers and an attentive audience who were very interested in performance analysis and capacity planning in general, in addition to it's applicability for ORACLE.

Just as an aside, if you look at the Hotsos company logo at the top of their web pages, you'll see some equations or bits of equations. The first of these is the denominator of the famous Erlang-C function (A. Erlang, 1917). More on that in an upcoming blog entry.

Looking for Guerrilla Class Pix

First, I should say Happy New Year! I don't think it's too late to say that. Is it? Personally, I've been buried in Mathematica since I came back from
CMG 2007
. In fact, I need a vacation!!!

Anyway, I'm looking for pix (JPEGs) that people have taken over the years while attending my Guerrilla classes. In particular, one year (2003, 2005?) there were some shots taken of the entire group outside the Crowne Plaza in the afternoon sunlight. I was emailed a copy of them at the time by the person who took them, but since upgrading computers N-times, I cannot find them. :-(

Please let me know if you have any such photos.