Some times we see the error below in the event logs:

“SQL Server has encountered 1 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [T:\MSSQL\DATA\%file_name%] in database [%DB_name%] (2).  The OS file handle is 0×00000838.  The offset of the latest long I/O is: 0x000000ebdc0000“

Do you refer it to as a stalled IO? We always hear a questions such as, what’s wrong with SQL Server..? Why is SQL taking so long to read or write to the disk..? Let us discuss why it is not a MS SQL Server problem:

MS SQL Server does data file reads and writes almost exclusively as asynchronous IO, using the win32 APIs ReadFile, WriteFile, ReadFileScatter and WriteFileGather. Each of these APIs behave in a fairly similar steps, the caller sends in a handle to the file, some memory location to read or write, the size of the block and a structure that tells the kernel how to handle the IO. In MS SQL Server’s case, how to handle the IO is Asynchronously, please.  The call returns immediately so that the thread issuing so that the IO can get out of the way and make life happy for other users who are also waiting got their query to return.

The catch here is that, ordinarily the time between the Asynchronous call to read or write and the completion of the read or write should be on the order of 10ms. The longer it takes for an IO to return the more noticeable a performance impact there is to end users.

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Here are some useful tools that help us in configuring IIS server to be more secure and less resource consuming:

1. IIS Passwords Sync:

IIS 6.0 web sites run under anonymous user accounts. It is IUSR_<machine name> (by default) or other user accounts created by your web hosting control panel. The users’ passwords are set automatically set and are never known. However, sometimes for some reason the passwords get out of sync or corrupted and need to be reset. The easiest way to reset these passwords is to use IIS Passwords Sync program. It extracts the passwords that Microsoft IIS 6.0 has in its metabase and updates the accounts in “Local Users and Groups” to use that passwords.

DOWNLOAD LINK

2. IIS Pool:

With IIS Pool tool we can easily search the problematic sites which have default application pool.

IIS Application Pools Monitoring and Analysis:

This program allows monitoring of IIS 6 application pools. All the monitoring data is stored in log files. It is possible to analyze a pool to find a website (or a virtual application) using too much resources. …

Overview -

IIS Application Pools Monitoring and Analysis:

* This program allows monitoring of IIS 6 application pools.

* All the monitoring data is stored in log files.

* It is possible to analyze a pool to find a website (or a virtual application) using too much resources.

Features -

* IIS application pools monitoring

* IIS application pools analysis

* Find websites using too much resources

DOWNLOAD LINK

3. IIS Report:

Overview -

IIS Report is a command line tool. It allows us to create different IIS related reports. For example it can get the list of all SSL websites and sort it by IP address, or get the list of all websites and sort it by application pool name and then by website name, …

There is no installation required. Just download and unrar the archive file. Then start the program with:

C:\>iisreport.exe /?

to get more information and see all the parameters available.

Benefits -

* Easy-to-use

* Fast

* It is possible to import the reports with Excel

* It is possible to parse the reports with VBS or BAT programs and other administration applications.

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