damn it :
26% free space. Have tried a 3rd defrag app, UltraDefrag. Have d/l Contig but can not get it to stay on the screen for more than a micro second. UltraDefrag reports these files with large amounts of fragments. What are these files? C:\$Secure:$SDS, C:\$Secure:$$II, and C:\$Secure:$SDH. There are over 3100 fragments in these three files, and can not be defraged by UltraDefrag.
Some files cannot be defragged. Some of what you ask is described below.
Best to leave these alone as they concern your disk volume Master File Volume.
$Secure (Security settings file contains unique security descriptors for all files within a volume) and is a resident file in the MFT (Master File Table).
As the MFT stores information about itself, the first 16KBs (first 16 entries) of the MFT for NTFS are reserved for metadata files of size 1KB. Each are used to describe the MTF in ascending order starting at, but excluding file zero (0), is as follows: $Mft (MFT – contains one base file record for each file and folder on an NTFS volume); $MftMirr (MFT mirror, guarantees access to the MFT in case of a single-sector failure. It is a duplicate image of the first four (4) records of the MFT); $LogFile (Log file contains a list of transaction steps used for NTFS recoverability and its size is dependent on the size of the volume); $Volume (Volume file contains information about the volume, i.e., label, version); $AttrDef (Attribute definition table lists attribute names, numbers and descriptors); \ (Root directory); $Bitmap (Volume cluster allocation file showing free and unused space); $Boot (Boot sector including the BIOS Parameter Block (BPB) used to mount the volume and additional bootstrap loader code used whether the volume is bootable); $BadClus (Bad-cluster file contains bad clusters for a volume); $Secure (Security settings file contains unique security descriptors for all files within a volume); $UpCase (Uppercase character mapping converts lowercase characters to matching Unicode uppercase characters); $Extend (Extended metadata directory, used for various optional extensions such as quotas, reparse point data, and object identifiers); (file 12 through to 15 are reserved for future use); Used files and directories.