"Sparse Checker": The utility for sparse files creation and management

This tiny application can free you some additional disk space normally occupied by continuous ranges of zero-bytes inside your files. With "SparseChecker" you can quickly and easily analyze the file and decide if it makes sense to optimize the occupied disk space marking the file as a sparse. The mechanics behind this process is the rarely used but yet available on all NTFS volumes "Sparse Files" technology introduced by Microsoft®. There are certain types of desktop applications that produce this kind of files. These are: virtual machine creation/management software, download clients, databases, scientific software that produces lots of data using the disk file pre-allocation technique, and much more ...

Download the installation of the "SparseChecker" if you already know what are you looking for:
Version: 0.3
Release date: 28 Apr 2011
Supported platforms: Windows XP/Vista/7
License: Freeware
User interface: GUI, Console
[Download (~633KB)]
MD5 Check sum: 3325F5A6C70E7D42AFA01BE7EF0DBB2A


In order to install the "SparseChecker" download the installation executable, run it and follow the instructions provided by the installation wizard. Installation package contains both command line and GUI versions of the "SparseChecker". Refer to "How to use the SparseChecker" chapter to find out more about the GUI version of this tool. As for the command line version - refer to "How to use the command line version of the SparseChecker" chapter.

How to use the "SparseChecker"

To find out whether some file needs to be marked as the sparse file execute the "SparseChecker" GUI and select the file in the edit box at the top. When the file is open and the basic statistics has been displayed in the log console window press the "Analyze File" button. The analysis starts and the results are being displayed during this process in the log console. Depending on the file size and file contents the analysis may take some significant time. Check the progress bar under the selected file edit box to estimate the analysis progress. Here is the screen shot demonstration the analysis of some large file:
On the screen shot we see that the some file has been selected for analysis. The messages in the log console show the process of analysis as well as the resulting summary information. In this particular case we see that the estimated profit is about 2GB of the disk space which is currently occupied by our file. Each line on the log console informs the user about the detected zero range. It reports the offset of the range from the beginning of the file as well as the size of the range. Although this information is not practically very useful to the casual user it may be interesting for enthusiasts and researchers providing the layout of the file by means of zero ranges located in it.

In order to free these mentioned 2GB of the disk space press the "Mark Sparse Regions" button. Note that you can't do this without performing the analysis first. Marking the sparse regions causes the disk space occupied by zeros to be released.

The following screen shot demonstrates the result of the sparse file marking operation:
sparse_checker_profit.png As you can see our file have just lost proximately 2GB remaining virtually the same, by means of the contents. When some application tries to read this file it gets the correct data including these mentioned zero ranges. If some information has been written to such a sparse file and if the data is written over the sparse region - the file just "grows" having all applications working correctly.

How to use the command line version of the "SparseChecker"

Imagine that we have some 200 MB file under c:\test\test_file.txt Let's use the sparse_checker to see how much of the disk space we can save making test_file.txt a sparse file.
We are going to use the "-a" option which stands for analysis to find out how much of the disk space can be saved for some particular file. Executing "sparse_checker.exe -a " gives us the following:

As we can see ("Space to be saved: 235.7 M") turning our file into a sparse file could give us about 235 MB of free space normally occupied by zeroes.

In order to optimize the file (make it sparse) the following parameters must be provided to sparse_checker.exe "sparse_checker.exe -s ". Effect can be seen with Windows Explorer like in case with the SparseCheckerGUI (see above).

Related links:
  1. NTFS Sparse Files For Programmers
  2. Fsutil sparse
  3. NTFS Sparse Files

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