SQL Server Transaction Log Backups

When you backup the SQL Server transaction log, the log is truncated by default. The space that has been consumed by transactions is freed once those transactions are backed up. Backing up the transaction log of a database throughout the day allows you to recover to the point of failure or any point in time. In addition, because databases that are set to full or bulk logged recovery models do not truncate the transaction log during full or differential backups, it may be essential to backup the transaction log periodically just to truncate the log.

If you allow the transaction log of a database to become completely filled, users will be denied write access to the database until you clear the transaction log. Scheduling regular backups of the transaction log can prevent this from happening. When the log is full, users may still execute read-only SELECT statements against the database. You can also prevent the transaction log from filling up by enabling autogrowth on the transaction log.

Just as you can backup the database using SQL Server Management Studio (SSMS), you can backup a transaction log in the graphical interface. Just be sure to select the Backup Type of Transaction Log. The T-SQL command for backing up the transaction log for the AdventureWorks database is as follows:

BACKUP LOG AdventureWorks To DISK='C:BACKUPSAWorksTlog.bak';

The preceding content excerpted from SQL Server 2008 Administration by Tom Carpenter.

Windows Command Line – 64-bit?

I've had a lot of people ask me about the 64-bit edition of Windows 7 and whether it has a 64-bit command line. The answer is yes and no. In this post, I'll explain what I mean.

First, if you launch the Windows command line (cmd.exe) on a 64-bit edition of Windows 7 and then look at the Task Manager, you'll notice that the process entry for cmd.exe does not have an *32 after it. This indicates that the cmd.exe process is 64-bit. You may notice several entries in the Task Manager with the *32 after them. These entries are for 32-bit applications and processes.

Now, the question is this: are all the Windows 7 command line commands also 64-bit now? The answer there is: It depends?

You see many of us have old habits that die hard. As long as you use 64-bit commands, while in cmd.exe, you will be using 64-bit command line tools; however, if you run a 32-bit command that command will still run, but it will be in 32-bit mode.

To see this, open the task manager and then open the command prompt from the Start menu on your Windows 7 64-bit machine.

Now change to the C:WindowsSysWOW64 directory in the command prompt window and then execute the more command with no parameters. It will appear to hang, but that's OK.

Look at the task manager and note the entry for the more.com command. It has an *32 after it.

You see, the files in the C:WindowsSysWOW64 folder are 32-bit commands. There is even a 32-bit version of cmd.exe that you can launch from there.

The point is simply this: To ensure that you are running a true 64-bit command prompt, make sure that all of your commands are 64-bit and not just thecmd.exe.