First investigation of Windows Azure

admin — Sun, 29 Nov 2009 20:01:41 +0000

So I have finally found some time to experiment with Windows Azure. My starting-point is that I’m a freelance developer that needs hosting services in order to try out several different ideas of my own.

I first wanted to get a better understanding of what a virtual machine looks like in Windows Azure. What is it exactly? I know it’s a Microsoft Windows Server box running on Hyper-V, at least that is what Microsoft has told me. But then what? Read on to discover some of my findings. Note, however, that I’m not an expert and I’m sure that some of my findings and questions could be answered by reading documentation somewhere but I like to get my hands dirty by looking under the hood.

Operating System Environment

My virtual machine (vm) in Windows Azure is running the following version of Windows::

Microsoft Windows NT 6.0.6002 Service Pack 2

Which translate to the marketing name of “Windows Server 2008″, that is NOT R2 (yet, anyway).

Also, it is running:

Microsoft.NET version 2.0.50727.4016

I have a Small VM and therefore should have 1,7 Gb of memory in total, which I also verified and got the exact number back:

1,877,766,144 bytes of total memory

Not that it matters but I also found my machine name to be “RD00155D3141A4″ and part of the domain “CIS”.

File System Organization

The organization of the file system is more interesting. On a newly created vm and deployed web role I can see three drives:

C: has a total of 225 GB of which 218 GB are free
D: has a total of 16 GB of which 8 GB are free
E: has a total of 1 GB of which almost all are free

After investigating their contents I can determine that D: has the installed operating system with the usual “Program Files” and “Windows” folders. E: has my deployed web role in the E:\approot folder and just some additional support/config folders and files (I assume!).

The C: drive is the stranger drive. It has a “dumpfile.dmp” and a “pagefile.sys” file which I recognize as Windows files. There are also folders with names such as “Applications”, “Config”, “MOSLogs”, “OS”, “Packages”, “Resources” and the known “System Volume Information”. Some are empty but not all (I’ll get back to that.

When I upgrade my web role with some changed code, the E: drive is kept an F: drive appears. So it looks like at least a few versions of deployed roles will be kept at different drive letters.

The different vm sizes specifies that I should have 250 Gb of storage for “Disk Space for Local Storage Resources” so this must be the C drive. I don’t have write access to all of it though, but I probably just haven’t found where you are supposed to put such files. In any event, I assume that you must be prepared for that storage to vanish at any given moment. For sure if you delete and recreate your vm.

Processes

I have also tried to enumerate all running processes in the machine and I ended up with the following list:

id	name	path	MB	start time	cpu time
2352	clouddrivesvc	Access is denied	5	Access is denied	Access is denied
456	csrss	Access is denied	5	Access is denied	Access is denied
496	csrss	Access is denied	5	Access is denied	Access is denied
0	Idle	Unable to enumerate the process modules.	0	Access is denied	Access is denied
1968	LogonUI	Access is denied	15	Access is denied	Access is denied
592	lsass	Access is denied	11	Access is denied	Access is denied
600	lsm	Access is denied	6	Access is denied	Access is denied
2772	MonAgentHost	E:\diagnostics\x64\monitor\MonAgentHost.exe	14	11/29/2009 3:40:48 PM	00:00:00.1718750
2504	msdtc	Access is denied	8	Access is denied	Access is denied
1212	osdiag	Access is denied	6	Access is denied	Access is denied
1876	rdagent	Access is denied	23	Access is denied	Access is denied
580	services	Access is denied	6	Access is denied	Access is denied
260	SLsvc	Access is denied	11	Access is denied	Access is denied
392	smss	Access is denied	1	Access is denied	Access is denied
1252	svchost	Access is denied	3	Access is denied	Access is denied
2088	svchost	Access is denied	6	Access is denied	Access is denied
1360	svchost	Access is denied	6	Access is denied	Access is denied
296	svchost	Access is denied	8	Access is denied	Access is denied
1280	svchost	Access is denied	12	Access is denied	Access is denied
1376	svchost	Access is denied	3	Access is denied	Access is denied
844	svchost	Access is denied	7	Access is denied	Access is denied
404	svchost	Access is denied	7	Access is denied	Access is denied
940	svchost	Access is denied	19	Access is denied	Access is denied
224	svchost	Access is denied	13	Access is denied	Access is denied
416	svchost	Access is denied	31	Access is denied	Access is denied
776	svchost	Access is denied	7	Access is denied	Access is denied
1232	svchost	Access is denied	6	Access is denied	Access is denied
708	svchost	Access is denied	10	Access is denied	Access is denied
4	System	Unable to enumerate the process modules.	8	Access is denied	Access is denied
1808	vds	Access is denied	8	Access is denied	Access is denied
1164	vmicsvc	Access is denied	5	Access is denied	Access is denied
1152	vmicsvc	Access is denied	4	Access is denied	Access is denied
2056	WaWebHost	E:\base\x64\WaWebHost.exe	95	11/29/2009 3:40:33 PM	00:00:16.9531250
504	wininit	Access is denied	5	Access is denied	Access is denied
532	winlogon	Access is denied	5	Access is denied	Access is denied

Not that interesting perhaps, but I can determine that my deployed web role has spawn the WaWebHost.exe and the MonAgentHost.exe processes. Maybe more information could be read, but I’m leaving this part of the investigation as it is for now.

Web Role

So how is the code in my web role actually run by Azure? I can see these things:

The exact code for the built/published web project is stored in E:\approot. There are my Global.asax, Web.config, bin-folder and so on.
The process that has been spawn to run this code is stored in E:\base\x64\WaWebHost.exe. I think this exe file is actually contained in the deployed packade, which means I can control this executable if I so wish?
There is no w3wp.exe process running so it seems that IIS is not doing any work at all to run my code. I’m guessing though that WaWebHost.exe may be a special version/compilation of w3wp.exe for Azure?

Now, the most important question I would like to answer in this first investigation is if, and if so how, I can run multiple sites or web projects in a single vm. Knowing IIS, I should go looking for applicationHost.config and see how it points to the web site folders (E:\approot according to the investigation so far).

In fact, I find IIS in its usual place at D:\Windows\System32\inetsrv in my vm. There is also an applicationHost.config in the config sub folder, but it has nothing pointing to E:\approot.

However, I did find the file at C:\Resources\Temp\63a1a1bad2fd41729fe654d54ada5d05.PublicRole (a generated folder name that will look different on other vm:s, for sure). There I can see:

An Application Pool that is running as “NetworkService” (the only one).
A web site with the name “Role Site” and a mapping of the root “/” to “E:\approot\”.
A binding for this site to ip 10.115.141.65 on port 20000 (no host name).

So my vm has a local network address behind Azures load balancer (or gateway or whatever it is called) and it is routing incoming traffic on port 80 to port 20000 on my vm.

The obvious question is if I can change this applicationHost.config file and thereby point it to sub folders in my web role, which would then actually represent different sites or web projects in Visual Studio. I just had to try! Unfortunately nothing happens when I added another site to this file. And since it is in a Temp sub folder I assume it is only used when WaWebHost.exe starts up. I also tried suspending the vm and than starting it again (not sure if this is the same as rebooting the vm?). But then the file is overwritten and my new site info is gone. Too bad, but of course if it was supported there would be an easier way to do it than such a hack.

Conclusion about suitable scenario

One thing I’ve come to realize is that Windows Azure (of today, at least) is not a substitute for a VPS or dedicated server of my own. My first attempt was to find out if Windows Azure actually could be the solution to all of my hosting needs, and it is probably not. Even if it would work, it is obviously not designed for handling multiple sites.

Windows Azure is for when one of your ideas or projects has gotten enough attention or quality that it is time to launch to the public and be prepared for both success and failure. You will be able to scale up to any size you need, and you will also be able to shut it down literally within minutes without any additional costs. Of course, you’ll have to pay for the time between those two events: the launch and the decision.