Friday, May 9, 2014

How to determine the Windows Master File Table (MFT) Size

In my series of articles related to Windows Master File Table (MFT),  let's understand how to get this size of MFT on you disk.

The common approach is to issue the following command

fsutil fsinfo ntfsinfo C:

This yields, and we can see the field label MFT Valid Data Length, but for busy administrators this hex value is takes to much time to deal with.

Luckily for the excellent team at Sysinternals produced a tool to get around these hexadecimal numbers.

NTFSInfo is a little applet that shows you information about NTFS volumes. Its dump includes the size of a drive's allocation units, where key NTFS files are located, and the sizes of the NTFS metadata files on the volume. This information is typically of little more than curiosity value, but NTFSInfo does show some interesting things. For example, you've probably heard about the NTFS equivalent of the FAT file system's File Allocation Table. Its called the Master File Table (MFT), and it is made up of constant sized records that describe the location of all the files and directories on the drive. What's surprising about the MFT is that it is managed as a file, just like any other.

Download NTFSInfo, save in C:\windows\system32 path, so you can run it from the command line as Administrator

ntfsinfo C:

This yields 

From here we can see this drive has a MFT Size of 160 MB out of out of 129.6 Gb, leaving 
126.99 Gb of space that can be used. Roughly 0.1 % of the drive space after it has been formated.

The actual disk size can be found running MSINFO32 (Start->Run->msinfo32).

So this disk, after formatting has lost 350Mb for partitioning (reserved disk) and 2*160Mb for NTFS MFT overhead for a total of 670Mb or ~ .7Gb out of 126.99 Gb disk or 130Gb advertised space.

Search my other posts on this and a tool I created for this. 

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