Here are the numbers for the data structures used by defrag, when calculated for FAT32.
Cluster movable map: 32 MB (fat size * 1 bit) FAT refered map: 32MB (fat size * 1 bit) FAT refered table: 1024MB (fat size * 4 byte) Dir refered table (take 100000 files): (# files * 6 bytes) 0,5 MB total: 1088,5 MB (and I though XMS only went to 64MB) In depth: Cluster movable map: indicates which clusters are movable. FAT refered map: indicates which clusters are refered to in the FAT FAT refered table: stores the back pointers for the FAT clusters DIR refered table: stores the back pointers for the directory refered clusters Imre >----- Oorspronkelijk bericht ----- >Van: Eric Auer [mailto:[EMAIL PROTECTED] >Verzonden: dinsdag, maart 18, 2008 10:22 PM >Aan: [email protected] >Onderwerp: Re: [Freedos-devel] Fwd: freedos defrag methods (OT) > > >Hi! > >> For this it is very sad that FreeDOS does not use the LEAN file system >> (http://freedos-32.sourceforge.net/doc/lean.html) instead. That has back >> pointers for pretty much everything and would as a consequence be much >> faster. > >A lean ad ;-). But you can just as well build data structures with the >back pointers in RAM while defrag and similar tools are running. Takes >roughly the same amount of RAM as the metadata (FAT, dir) takes on >disk. As you often copy those to RAM for work like defragging to get >fast access, you basically get some overhead for making the pointers >plus you double the amount of RAM that defrag consumes ;-). > >Note that for example DOSFSCK takes several times the size of your FAT >plus several times the size of all directory entries of RAM, too. >Actually this would be interesting to know more about: Could some of >you run DOSFSCK 2.11c with the -v option on large filesystems, with >many files and/or many clusters, and report how much heap it tells >you that it has used? It is displayed when DOSFSCK is done. Seems to >be 5..10 times the FAT size for systems with few files here... Some >"bad case of FAT16" would be interesting (might use 1-5 MB maybe?) >as well as, of course, typical FAT32 filesystems. You can find >DOSFSCK version 2.11c on my page, as usual: >www.coli.uni-saarland.de/~eric/stuff/soft/by-others/dosdosfsck-2.11c.zip >(you should already have cwsdpmi anyway, otherwise see e.g. my page) > >Eric > > > >------------------------------------------------------------------------- >This SF.net email is sponsored by: Microsoft >Defy all challenges. Microsoft(R) Visual Studio 2008. >http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >_______________________________________________ >Freedos-devel mailing list >[email protected] >https://lists.sourceforge.net/lists/listinfo/freedos-devel > > ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Freedos-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freedos-devel
