Not very often, you will get the following error:

Error:
The server principal “” is not able to access the database “” under the current security context.

This is because the MS SQL Server is attempting to execute a SQL query to retrieve a list of databases along with  some other formation about those databases. Some of  that information is “Collation”, which, ofcourse you don’t have permission to view for all databases, since  you’re in a shared hosting environment and you can only have access to your database..

Solution is pretty straight forward :
1. In Object Explorer, click on Databases
2. Display Object Explorer Details (F7) or View > Object Explorer Details
3. Right click the column headers and de-select “Collation”

4. Refresh Databases or reconnect to ste machine.

Thats it

Bye bye 

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.

Microsoft SQL Server 2005/2008 Express is a free edition of SQL Server that is ideal for learning, developing and powering desktop, web and small server applications, and for redistribution by ISVs.

Top Features

First, we need to have a query that will backup all databases to one folder… Well, here it is


DECLARE @name VARCHAR(50) -- database name
DECLARE @path VARCHAR(256) -- path for backup files
DECLARE @fileName VARCHAR(256) -- filename for backup
DECLARE @fileDate VARCHAR(20) -- used for file name
SET @path = 'E:\sqlbackups\' --path to the backup folder
SELECT @fileDate = CONVERT(VARCHAR(20),GETDATE(),112)
DECLARE db_cursor CURSOR FOR
SELECT name
FROM master.dbo.sysdatabases
WHERE name NOT IN ('tempdb')
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO @name
WHILE @@FETCH_STATUS = 0
BEGIN
SET @fileName = @path + @name + '_' + @fileDate + '.BAK'
BACKUP DATABASE @name TO DISK = @fileName
FETCH NEXT FROM db_cursor INTO @name
END
CLOSE db_cursor
DEALLOCATE db_cursor

This will backup everything except the “Temdb” database. So, lets take a look at the current state of our backup folder.

As we can see, only the backups from 21.11.2009 exist. So, what happens when we run the query using SQL Management Studio.

Here’s the query pasted in “New query window”.

Sooo…if everything went smoothly, we should get a message similar to this one :

Awesome! Now, lets take a look at our backup folder, are there any changes? Sure hope there is, because this post will totally suck if the backup didn’t complete

As we can see, this post will not suck after all Notice the new files, created on the 22.11.2009 . IT WORKS! All we have to do now is to automate the backup, so we don’t have to run the query everyday by hand.

We will do that using Task Scheduler (or Scheduled tasks in Windows 2003). We have to add a task to execute everyday in 3 AM.

The command we have to run is:

“C:\Program Files (x86)\Microsoft SQL Server\90\Tools\Binn\SQLCMD.EXE” -i “c:\pathtosqlquery\sqlbackup.sql”

Where “sqlbackup.sql” is the name of the file you have pasted the code mentioned before.

Here are a couple of pictures so you can see how to do it:

Now, click on “Create task”. That will click will start the task wizard. Enter the name of the task ( i.e “SQL Backups”.

After entering the name and choosing the option “Run wheneter user is logged on or not”, click on “Triggers”.

Click on “New”. It will bring up a new window

Choose the “Daily” option, and set the time when you want the task to run. I have set it to 3 AM .

ONE IMPORTANT THING!!! Dont forget to check the “Enable” checkbox , otherwise, you will end up scratching your head and cursing Microsoft and uncle Bill hehe.

After that, click on “Actions”, where we will define the program that should be runned… Click on “New”…

Paste this into the “Program/Script” box.

“C:\Program Files (x86)\Microsoft SQL Server\90\Tools\Binn\SQLCMD.EXE”

NOTE! – path to the “SQLCMD.exe” may be different on your system!!!

All that is left to do is to “Add arguments”

-i “c:\pathtosqlqueryfile\sqlbackup.sql”

Click on “OK”, enter the system password and thats it. Enjoy your daily backup.

HINT!!!! If you’re lazy like I am, you can use a powershell script to delete backup files older than X days. I have also covered that with a blog post. More info about that on this link.

Bye bye!

Hello there…

In order to  install SQL 2008 Express, we have to download it first . Fire up your favorite browser and point it to http://www.microsoft.com/express/download/ . After that, find the box with the SQL 2008 Express, and click download.

On the next step you have the option to register with Microsoft or download the software without registration.  I will choose the “no registration part”.

In the new window, choose the version you would like to install. Personally, I will choose “Runtime with advanced services“. By clicking on install, Microsoft will ask to install the Microsoft Web Platform installer. If you dont have it installed, click on the picture to install it.

Choose “Run”, and after the download, again, choose “Run“. Wait for the installtion to finish and look at the top of the browser, a little bar will pop up and ask us if we want to run Active X control.  Make sure the publisher is “Microsoft Corporation”. Click on “Run“, and then on Allow.

Now, look at the video of the installation I have made for you. The video will show you the process of installing SQL Server 2008 Express.

After that, all you need to do is run the “SQL Server Configuration Manager” under “Configuration Tools” and configure it the way you want it.

BTW, the track used is La Noche by Coca & Villa .IT’s AWESOME!!!

Have fun…bye!

Hi, last couple of days I have setuped over 10 Windows 2008 servers for hosting services for testing or production, so I am pretty bored with repeating the same stuff all over again , but, here’s a recorded video tutorial of one installation process. Because the video is pretty straightforward, I’ve decided that there is no need to explain every step of the installation.

Click on the HD button and put the video into full screen mode, so you can see all the details.

In the next post, I will show you how to install Microsoft SQL server 2008 Express .

Cheers!

How many time did you find yourself in a situation where you need a reliable, stable and strong server? How to even determine if your server is stable enough? How to know what kind of continous load can it handle? Will it crash if it gets under heavy load for a couple of hours?  Well, today, I’ve found myself in a situation like that. I have installed HyperV on some server we have at the office and wanted to see how it will perfom under extreme heavy load and how stable everyhing was .

By extreme heavy load I assume about 200 concurent users clicking every 1-3 seconds on a random page that is being served on the server . When you look at the number of 200 concurrent users, you can say: ” Hey, 200 users isnt that big of a number for a server to handle” …and you would be absolutely right … if the server i was trying to “kill” didnt have 1 cpu core and 1 gb of ram assigned to it .

So..the point was to simulate real life conditions as much as possible. To do that, once more, I turned to Linux and the little piece of awesome software called “Siege”. You can download it here.  The software is able to simulate almost real user like behavior on a web page.  It can randomly open link in a specified interval, simulate 200+ users at the same time without any problems and so on.

To do some proper testing I’ve installed some php+mysql and asp.net+sql2008 applications to simulate a real-life scenario as much as possible. As we all know, one of pretty hungry applications for Linux is Joomla for the PHP+MYSQL combination and DotNetNuke for ASP.Net and MSSql combination. All cacheing  techniques on the application and the IIS were turned off so we can maximize the load to the server.

The server is based on Windows 2008 Server R2 Standard Edition and SQL Express 2008 .

I’ve told Siege to simulate 100 users on the Joomla site and 100 users on the ASP.Net site for 24 hours.  At this moment, tests are running for 6 hours and everything seems to be in perfect order. Here’s a couple of pictures

As we like to say it..BURN BABY BURN! About 16 more hours to go under 100% cpu Results are coming soon…in about 20 hours more or less ….