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Microsoft's FAT to NTFS conversion tool has been doing this sort of thing for years, too. It just puts the NTFS master file table and other stuff into the FAT
by JdeBP 7y ago
Microsoft's FAT to NTFS conversion tool has been doing this sort of thing for years, too. It just puts the NTFS master file table and other stuff into the FAT free space, or a designated file. Of course, being a conversion tool the intent was that both sets of data structures described the same files.
* https://docs.microsoft.com/en-gb/windows-server/administration/windows-commands/convert https://docs.microsoft.com/en-gb/windows-server/administrati...
Equally interesting are the tools that convert from the "MBR" style partition table to EFI partitioning. Again, this requires that the MBR-style partition table have free spaces into which the EFI partition table can be put. They have to be in fixed positions, though, unlike the NTFS MFT.
- asdfaoeu 7y agobtrfs has a similar convertor with the other quirk that the source ext partition remains as a file in btrfs and deleting it "commit"s the conversion. https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-convert https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-conver...
- cmurf 7y agoSmall quibble, the original file system, named ext2_saved, is a subvolume/snapshot. As long as it's kept around, you can revert the conversion while losing any changes made to the Btrfs file system. The comments explain the strategy in some detail. ReiserFS conversion is supported in addition to ext[234]. Because Btrfs requires only a little fixed space, just its superblocks, in theory any file system could be converted. https://github.com/kdave/btrfs-progs/blob/master/convert/main.c https://github.com/kdave/btrfs-progs/blob/master/convert/mai...
- JdeBP 7y agoThe difference here, though, is that NTFS does not have BTRFS's reserved area at the start of the volume. The BTRFS converter has to relocate foreign data structures out of that reserved area, meaning that the volume is not simultaneously both the old and new formats. Ironically, given what I mentioned, this conflicts most heavily with FAT. Whereas the only fixed-position data structure in NTFS is the BPB in the Volume Boot Record, which it can even mostly share with FAT. In the FAT to NTFS conversion there is a point where (BPB aside) the two sets of filesystem structures are simultaneously valid.
- Sohcahtoa82 7y ago> btrfs Is this usually pronounced as individual letters (bee tee arr eff ess), or like "butter FS"? EDIT: Wikipedia [0] says it's pronounced many ways, such as "butter fuss", "better F S", "butter F S", "b-tree F S", or simply by spelling it out. [0] https://en.wikipedia.org/wiki/Btrfs https://en.wikipedia.org/wiki/Btrfs