Tag Archive: windows

SCVMM? errr…System Center Virtual Machine Manager and HyperV whining :)

Posted Jun.10, 2011 under News, Servers

Couple of days ago I installed SCVMM  in order to test it out, since we are developing our IAAS solution. Everything seemed great until I found out that SVCMM doesnt have any API which can be used to create/turn on/off  new machines.  Yes, I know everything can be scripted thru Powershell, but it sucks that we need to create separate applicatons that will give us that feature. Imagine a solution where PRTG, Nagios or any other tools monitors your server… sees that the CPU load went up ( or any other condition) and starts up a new virtual machine  using API?

Its funny how the guys at MS fails to see the basic requirements for a modern cloud solution; do I have to mention that after years of HyperV being RTM-ed, we still dont have an option to limit a machines uplink speed!? Come on guys…SERIOUSLY!?!?

 

I know that you already have this  little piece of software created, release it…pretty please!? I know that Microsoft sees HyperV in some giant corporation where they dont have a need to limit the uplink of a virtual machine, but IMHO, hosters are having a bigger “market” share  than big corporations, think about us, pretty please with sugar on top :) .

Oh, what about promiscous mode for network cards? You  have no idea how much would I like to use SNORT on my HyperV virtual switch, but…I cant :(

What about the limit on only 4 cores per virtual machine? This is a VERY limiting factor. I’m in a situation where i have a 2x six core, 48 GB ram server which I want to turn into ONE virtual machine ( live migrations, scaling, etc…), but I cant…I can only turn it into a 4 core, 44 GB machine, effectively, wasting other 8 cores!?

I would really love to get in touch with someone from Microsoft Virtualization team and send them a list of must-have changes :D Someone knows some insiders? :D

Let me make one thing clear, I love Microsoft, but lets face it, there is lots of work that needs to be done. Admit it or not, the guys at the “Linux Camp” have much more options and features regarding virtualization. I really, really love HyperV, but some limitations are just plain unlogical/stupid.

Sorry for a bitter post, but I had to throw out my frustrations :)

 

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WebSitePanel – MySQL problem fix – UPDATED

Posted Apr.28, 2011 under WebSitePanel Fixes

Here you can download the files for fixing mysql issues ( deleting database ) on WSP 1.0.1.0, 1.0.2 , 1.1.0 and 1.1.2

INSTRUCTIONS :

Replace “websitepanel.providers.database.mysql.dll” file in “server\bin” folder with the one you downloaded. These fixes fixed my problem on all servers EXCEPT the one running mysql 5.0.27 version….ones runing 5.1 and 5.0.77 works fine. I Will update if I get this solved too…

Currently I am getting this error on 5.0.27 server: ERROR: ‘MySQL Server 5.0′ DeleteDatabase System.Data.EvaluateException: Cannot perform ‘=’ operation on System.Byte[] and System.String.

FIX for 1.0.1.0 version can be found HERE

FIX for the 1.0.2 version can be found HERE

FIX for the 1.1.0 version can be found HERE

FIX for the 1.1.2 version can be found HERE – UPDATED!!!

Hope it will be helpfull.

If you have any questions, just let me know.

Ofcourse, these fixes are provided AS-IS . I dont guarantee it will work on your machine, and I cannot take responsibility for any damages cause by it.

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SpamBots+bad application+SQL server = PROBLEMS!

Posted Oct.25, 2010 under Servers, Windows and Powershell

So…today I had a very interesting issue. All of a sudden Nagios went red with the message: CRITICAL : – total: 232.82 Gb – used: 212.67 Gb (91%) – free 20.15 Gb (9%) on one of our SQL server. I was like..”NO! It cannot be. I clearly remember that this machine had over 150 Gb of free space yesterday!”

I log in to the machine, and automatically go to the data folder of SQL server thinking that some customer has a HUGE! log file on his database; so, right click – Select All -> Properties… only 50 Gbs of data…hmm…not here!

At that moment I notice that the server isnt “jumpy” as usual, so I start Performance monitor and see that the Avg. Disk Queue is off the chart!  That definatelly isnt right…

Since that machine is using Windows 2003, theres no too good way to see what application is using so much disk I/O ( beside FileMon ) , I start the FileMon and se that the SQL service is writing HUGE amount of data to its ERRORLOG file.

By navigating to the folder, I see that the ERRORLOG file is over 120 Gb big so opening it in Notepad, Context or some other file was out of the question, since it would kill the machine completely.

So, lets turn to powershell once more. In order to be sure to not kill the machine, since its in production , I have moved the file to an empty machine to opened it there.

Powershell : cat errorlog +ENTER :) after that powershell started to list the entire content of the file, and it took about 15 mins until it reached the end. AMAZING

By examining the log, I notice ( it was hard to NOT notice it ) litterally millions of these entries:

Could not allocate space for object ‘dbo.tblComments’.'tblComments’ in database ‘DATABASEname’ because the ‘PRIMARY’ filegroup is full. Create disk space by deleting unneeded files, dropping objects in the filegroup, adding additional files to the filegroup, or setting autogrowth on for existing files in the filegroup.

What happened here?

The site that was using that database is poorly written and was allowing everyone to post comments on the articles without any security check, so it soon reached the size limit set on the database.  By further digging on the issue, I saw that the bots are posting about 4-5 comments each second which comes to about 18000 comments/hour…multiply that by 15-16 hours it took to fill the error log to that size, we roughly come to 280000 comments…that’s A LOT of comments! :)

After disabling the site and sending the email to the customer, situation on the machine looks like this :

The big drop on the green line is the moment where I disabled the problematic web site.

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Using compression on IIS servers? Yes or no?

Posted Oct.08, 2010 under IIS server, Servers, Windows and Powershell

Well…in the very beginning, my answer is pretty much simple : yes AND no!  Why you ask?  Just keep reading…

Compression, regardless if its the compression of static or dynamic content is using CPU – that is a fact we can all agree upon.

Lets say compression is a tradeoff – CPU for bandwidth..use more cpu to “burn” less bandwidth.

The big question here is how to decide if you will benefit from turning on compression or not.

Most of us have “multi-purpose” servers which run various roles at the same time ( database server ( MYSQL , MSSQL, etc…) , mail server, web server, etc.. and all of those services are spending a certain amount of CPU time.

By turning on the compression, you will automatically “lose” some CPU time which could have been used for faster execution of some database queries i.e… Read More »

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Don’t run production ASP.NET Applications with debug=true

Posted Nov.29, 2009 under IIS server, Servers, Windows and Powershell

Found an awesome post on DotNetPanel blog so I had to repost it :)

One of the things you want to avoid when deploying an ASP.NET application into production is to accidentally (or deliberately) leave the <compilation debug=”true”/> switch on within the application’s web.config file.

Doing so causes a number of non-optimal things to happen including:

1) The compilation of ASP.NET pages takes longer (since some batch optimizations are disabled)

2) Code can execute slower (since some additional debug paths are enabled)

3) Much more memory is used within the application at runtime

4) Scripts and images downloaded from the WebResources.axd handler are not cached

This last point is particularly important, since it means that all client-javascript libraries and static images that are deployed via WebResources.axd will be continually downloaded by clients on each page view request and not cached locally within the browser.  This can slow down the user experience quite a bit for things like Atlas, controls like TreeView/Menu/Validators, and any other third-party control or custom code that deploys client resources.  Note that the reason why these resources are not cached when debug is set to true is so that developers don’t have to continually flush their browser cache and restart it every-time they make a change to a resource handler (our assumption is that when you have debug=true set you are in active development on your site).

When <compilation debug=”false”/> is set, the WebResource.axd handler will automatically set a long cache policy on resources retrieved via it – so that the resource is only downloaded once to the client and cached there forever (it will also be cached on any intermediate proxy servers).  If you have Atlas installed for your application, it will also automatically compress the content from the WebResources.axd handler for you when <compilation debug=”false”/> is set – reducing the size of any client-script javascript library or static resource for you (and not requiring you to write any custom code or configure anything within IIS to get it).

What about binaries compiled with debug symbols?

One scenario that several people find very useful is to compile/pre-compile an application or associated class libraries with debug symbols so that more detailed stack trace and line error messages can be retrieved from it when errors occur.

The good news is that you can do this without having the have the <compilation debug=”true”/> switch enabled in production.  Specifically, you can use either a web deployment project or a web application project to pre-compile the code for your site with debug symbols, and then change the <compilation debug=”true”/> switch to false right before you deploy the application on the server.

The debug symbols and metadata in the compiled assemblies will increase the memory footprint of the application, but this can sometimes be an ok trade-off for more detailed error messages.

The <deployment retail=”true”/> Switch in Maching.config

If you are a server administrator and want to ensure that no one accidentally deploys an ASP.NET application in production with the <compilation debug=”true”/> switch enabled within the application’s web.config file, one trick you can use with ASP.NET V2.0 is to take advantage of the <deployment> section within your machine.config file.

Specifically, by setting this within your machine.config file:

<configuration>

<system.web>

<deployment retail=”true”/>

</system.web>

</configuration>

You will disable the <compilation debug=”true”/> switch, disable the ability to output trace output in a page, and turn off the ability to show detailed error messages remotely.  Note that these last two items are security best practices you really want to follow (otherwise hackers can learn a lot more about the internals of your application than you should show them).

Setting this switch to true is probably a best practice that any company with formal production servers should follow to ensure that an application always runs with the best possible performance and no security information leakages.  There isn’t a ton of documentation on this switch – but you can learn a little more about it here.

So, dear developers, keep on eye on debug state…it will make you and the server happier :)

ALL CREDITS OF THIS TEXT GO TO DOTNETPANEL BLOG!

Source : DotNetPanel Blog

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