Peter Viola

When it comes to improving Windows server performance, most sysadmins focus on hardware such as adding CPUs or RAM. However, low disk space can also impact performance sometimes even causing critical processes such as backups to fail. Fortunately there are quite a few places to check on a Windows server to free up additional disk space.  Some paces to check are obvious such as cleaning up log files while other paces are not as obvious such as finding system temp files.

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How to See System Files

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Before searching for additional space you need to ensure that you Windows Explorer will display hidden system files and file extensions. To confirm you can see these open Windows Explorer and go to Folder & Search Options.

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Click on the View tab and select Show hidden files, folders, and drives. Uncheck Hide protected operating system files and Hide extensions for known file types.  Making these changes will allow you to see all the files on the server including system files and folders which could be taking up unnecessary space. Click OK to close the window.

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Before deleting anything always double check that you really don’t need the files any more and it’s safe to delete. Here are the top places that I check when I need to free up disk space on a Windows server.

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1. Empty Recycle Bin

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Cleaning up the recycle bin is most likely the easiest way to purge files unnecessarily taking up space. When you need to quickly clean up space this is the first place to check. It is surprising how much space can accumulate over time. Every disk volume on the server has a $recycle.bin folder. As mentioned above you won’t be able to see it until you enable viewing system folders. In the picture below you can see there’s plenty of deleted files waiting to be purged. Just select all the folders and right-click to delete them.

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2. Compress IIS Log Files

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The next thing I do when I need to free up disk space is to compress the IIS site log files. The default path to these files is %SystemDrive%\inetpub\logs\LogFiles. However, I prefer to redirect that path to something easier to find at the root of the disk drive such as C:\wwwlogs. If the server has multiple drives I will store them on the largest drive. Unless you disable your site logs they will automatically grow until the disk drive has filled up or they are removed or they are deleted. Enabling Windows file compression on the IIS logs directory tree will save a considerable amount of disk space.

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To enable Windows file compression, just right-click on logs folder and select Properties. Click the Advanced button and as shown in the picture above and select Compress contents to save disk space. Click OK to close the window. Depending on how much content you have in the directory tree it may take several minutes to complete.

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The picture above is from an IIS logs folder where I enabled compression and as you can see it saved 62% of the space being utilized by the log files. You can squeeze even more free space from your IIS log files by zipping them with an archiving program. In a recent walkthrough of mine I show how to manage IIS logs with GZipStream.

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3. Compress SQL Server Backups

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The SQL Server backup folder is another great place to check when you need to free up some disk space. You can use the steps above to apply Windows file compression and as well zipping the files to free up additional disk space. In the photo below the SQL Server backup folder is using 1.8 GB of space without any compression.

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After applying compression to this folder I was able to save approximately 60% of the disk space used by the backups. By zipping the files as well can you save can even more space. Depending on your particular business needs, you can also save additional disk space by limiting number of backups SQL Server stores on the server. This can be configured with a SQL Server Maintenance Plan.

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4. Cleanup Performance Monitor Reports

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Windows Performance Monitor is an invaluable tool to analyze performance on a Widows server. Within minutes, one can easily configure a Data Collector to get deep insights on CPU, RAM, Network IO, and Disk IO. However, this convenience can also lead to disk space being needlessly consumed when you have forgotten about the reports days or weeks after the analysis has completed. This will be even more apparent if someone forgets to set a Stop Condition on the Data Collector and leaves it running for days.

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The default path for the logs is usually C:\PerfLogs. The report path is also clearly shown in the Data Collector properties. Once your analysis has completed and you’ve reviewed the reports you can delete them. Applying Windows file compression to the reports folder as shown above will also help save disk space.

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5. Cleanup Windows Error Reports

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Windows Error Reporting is an exceptional tool for identifying issues on your server. Unless you delete the logs or disable the feature they will accumulate over time. The default path to WER reports is C:\ProgramData\Microsoft\Windows\WER and there are two sub-directories below it. You can delete the files in the folders but you should leave the 2 folders in place. This is another great place to apply Windows file compression to save more space.

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6. Cleanup Windows Temp Files

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There are several paths on Windows server’s that are used temporarily when installing updates or new programs. In many cases Windows will automatically delete these files after the installation has completed. However sometimes you’ll need to manually delete them yourself. One such folder is C:\Windows\ServiceProfiles\NetworkService\AppData\Local\Temp. In the picture below I was able to free up nearly 1 GB by deleting Malware Protection updates that had not been properly removed after they were installed.

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Here are some other possible locations to look for temporary files that can be removed:

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• C:\temp

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• C:\Users\Default\AppData\Local\Temp

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• %localappdata%\Microsoft\Windows\Temporary Internet Files

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• %localappdata%\Microsoft\Windows\Explorer

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• %windir%\ServiceProfiles\LocalService\AppData\Local\Temp

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7. Windows Disk Cleanup Tool

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Trying to remember all the paths to temporary files can be a daunting challenge for any sysadmin. Fortunately Microsoft recognized this as well. On Windows Server 2008 R2 and Windows Server 2012 or later,  you can get a Disk Cleanup tool like the one on the desktop versions of Windows. However, to take advantage of this you need to install the Desktop Experience feature which is available using the Server Manager’s Add Features Wizard. Just check the feature and then complete the wizard.

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After the server has been installed you can access the Disk Cleanup tool from the Control Panel. You will have a convenient way to clean up different types of temporary files including Windows Update files and Windows Error Reporting files.

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This tool is very helpful with cleaning up disk space. However, you should be aware that there will be some additional programs installed along with the Disk Cleanup tool which you may not want on your server such as Media Player. Here is a complete list of the programs that are installed with the Desktop Experience.

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8. Windows Server 2008

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All of the options listed above will also work on Windows Server 2008 systems however specifically on Windows Server 2008 SP2 servers you can make the service pack permanent and free up space by running the following command which should free up nearly 1GB of disk space on the server:

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• compcln.exe /VERBOSE:C:\temp\compcln.txt

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9. Windows Server 2003

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Windows Server 2003 “end of life” is July 14, 2015. If you haven’t started migration plans for legacy systems on that platform then you need to start planning for it asap. A great place to clean up space on Windows Server 2003 is to delete the hotfix uninstall files. Imagine my surprise when I logged into the server below to work on a low disk space situation and I found over 1 GB of these legacy files going back to 2011. There are also files in the C:\windows\$hf_mig$ folder that can be cleaned up. However, It’s always a good idea to wait at least a week or two before deleting these files in case you need to rollback one of the hotfixes.

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One additional way to free up space would be to create a symbolic link from one directory to another on a larger disk drive. Mark Russinovich’s free Junction tool makes it very easy to do this however you have to be careful when doing this or you can inadvertently cause problems for yourself. Be sure to make a backup before using it the first time.

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In Summary

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Having your Windows server run out of space can cause serious performance issues as well as prevent important backup processes from running. I covered several great places to check on a Windows server when you need to free up space. Always confirm that files are safe to delete before you delete them. Thanks for reading.

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