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       mhddfs  -  The  driver  combines a several mount points into the single


        mhddfs /dir1,/dir2[,/path/to/dir3] /path/to/mount [-o options]
        mhddfs /dir1 dir2,dir3 /mount/point [-o options]
        fusermount -u /path/to/mount

   fstab record example:
       mhddfs#/path/to/dir1,/path/to/dir2 /mnt/point fuse defaults 0 0

       mhddfs#/dir1,/dir2,/dir3 /mnt fuse logfile=/var/log/mhddfs.log 0 0


       with an -o option1,option2...  you can specify some additional options:

       specify a file that will contain debug information.

       0 - debug messages

       1 - info messages

       2 - standard (default) messages

       a free space size threshold If a drive has the free space less than the
       threshold specifed then another drive will be choosen while creating  a
       new  file.   If  all the drives have free space less than the threshold
       specified then a drive containing most free space will be choosen.

       Default value is 4G, minimum value is 100M.

       This option accepts suffixes:
              [mM] - megabytes

              [gG] - gigabytes

              [kK] - kilobytes

       For an information about the additional options see output of:
              mhddfs -h


       The file system allows to unite a several mount points (or directories)
       to  the single one. So a one big filesystem is simulated and this makes
       it possible to combine a several hard drives or network  file  systems.
       This  system is like unionfs but it can choose a drive with the most of
       free space, and move the data  between  drives  transparently  for  the

       While writing files they are written to a 1st hdd until the hdd has the
       free space (see mlimit option), then they are written  on  a  2nd  hdd,
       then to 3rd etc.

       df  will show a total statistics of all filesystems like there is a big
       one hdd.

       If an overflow arises while writing to the hdd1  then  a  file  content
       already  written will be transferred to a hdd containing enough of free
       space for a file.  The  transferring  is  processed  on-the-fly,  fully
       transparent  for  the  application  that  is writing. So this behaviour
       simulates a big file system.

       The filesystems are combined must provide a possibility  to  get  their
       parameters  correctly  (e.g. size of free space). Otherwise the writing
       failure can occur (but data consistency will be ok anyway). For example
       it is a bad idea to combine a several sshfs systems together.

       Please read FUSE documentation for a further conception.


       Distributed under GPLv3

       Copyright (C) 2008 Dmitry E. Oboukhov <>

                                 February 2008                       mhddfs(1)