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January 27, 2005
VM test with IO Meter
A few days ago I was talking to Devlin and he asked why we don't just run benchmarks on the VMs to see what performance they get. After thinking about that I decided it was a good idea. So today I setup and ran some initial tests.
The test was fairly simple and is outlined below:
- IO Meter Dynamo on each virtual machine
- IO Meter GUI running on Tibblefork acting as the manager
- Ran the default IO Meter Disk IO test
- Ran 6 tests each with 1 more virtual machine
The graphs below are the results of the tests. You will notice that with only one VM running it has very good performance then drops in half almost with 2 and then just a steady decline.
(The pictures seem to be too wide for the page so you may want to right-click on them and select view image.)
The default Acess Specification for IO Meter is:
- Transfer Request Size: 2 KB
- Writes 33% of the time and does reads the other 67%
- 100% random distribution of calls instead of sequential
Here is a link to the Excel spreadsheet of the results that were used to generate the graphs.
Posted by nekstrom at 02:06 PM | Comments (1) | TrackBack
January 25, 2005
IOMeter
I've done some further looking at IOMeter and it won't work for a monitoring tool for our overhead test. It is meant more as a benchmark tool. Meaning that it generates a work load on the system and sees how well it responds. Which makes for some interesting experiments. It may be useful to run IOMeter tests on multiple VMs at the same time to see the performance degredation. This would probably yield some interesting results that we could then use.
Posted by nekstrom at 02:34 PM | Comments (0) | TrackBack
January 20, 2005
Overhead Test Initial Impressions and Update
The overhead test configuration is progressing. Well actually it is ready to go. Over the last couple of days I figured out how to configure our labs switch, I also enabled the web configuration module for it so configuring it is very easy now. I figured out how to work the load balancer we got from OIT, that turned out to be a little bit of a pain but not bad. What I had the most trouble with was figuring out how our test network needed to be setup so that requests made to virtual machines through the load balancer would work. With Windows 2003 server you have to have the network setup so that the load balancer is the default gateway for the server. Currently each of the virtual machines has two network cards the second one being on a separate vlan where the load balancer is the default gateway. After I disabled the first network card, which also had a default gateway set, everything started working.
My initial impressions of the test so far is that with strictly static content we can put a lot of virtual machines on one box and have them all running without much problem. The current setup is nine virtual machines each with 250MB of ram and a single CPU. One problem with VMWare is that the virtual network cards are only 10Mb/s which I think makes them become network bound before anything else. I need to try the other vmware network driver to discover if it will give each VM a bigger pipe.
Currently with all 9 machines active and serving content to about 150 clients continuously we have about 65 percent CPU usage and the network is at about 90 Mb (what you would expect with 9 VMs that each have a 10 Mb pipe).
What I need to do now is run the actual tests. Meaning have the load balancer pointing at only one machine and then increse by one machine every couple of minutes. I'm afraid though that we are going to run into an issue of being network bound though which will make the tests less meaningful, hopefully the other network driver will work and give more throughput. I'll update this when I find out.
Update
The other network driver allows the virtual machines to have 1Gb connections so it looks like I need to change all of the other VMs.
Posted by nekstrom at 01:43 PM | Comments (0) | TrackBack
January 11, 2005
Overhead Test Progress
Dr. Windley came up with an idea to estimate the overhead created by VMWare. The setup is fairly simple. Have a load balancer in front of a group of virtual machines. The test is simple also, you run a simple download test and note machine statistics for the parent system. Start haveing the load balancer include more and more virtual machines in the test. Watch the parent machine statistics. If VMWare had no overhead the parent machine statistics should stay the same. We should be able to tell the overhead for each virtual machine by the increase in the parent machines stats.
The big assumption here is that the overhead added by the OS itself is very small. This may or may not be true. We will need to test that to see.
If you look here you can find the list of todos that we have still to work on as well as other miscellaneous thoughts regarding the test.
Feel free to comment there on under this entry.
Posted by nekstrom at 06:09 AM | Comments (0) | TrackBack