MKSNAP_FFS(8)           FreeBSD System Manager's Manual          MKSNAP_FFS(8)

NAME

     mksnap_ffs - take a file system snapshot

SYNOPSIS

     mksnap_ffs snapshot_name

DESCRIPTION

     The mksnap_ffs utility creates a snapshot named snapshot_name.  This name
     is a path in the file system to be snapshotted.  Typically this is under
     the .snap directory in the root of the file system, but it can be
     anywhere in the filesystem being snapshotted.  Snapshots can be listed
     using the snapinfo(8) command.

     After a snapshot is taken it appears as a file.  The size of the snapshot
     file is equal to the size of the file system from which it was taken.  It
     can be moved, renamed or deleted (which removes the snapshot).

     The group ownership of the file is set to "operator"; the owner of the
     file remains "root".  The mode of the snapshot is set to be readable by
     the owner or members of the "operator" group.

EXAMPLES

     Create a snapshot of /home file system and mount the snapshot elsewhere:

           mksnap_ffs /home/.snap/snap1
           mdconfig -a -t vnode -o readonly -f /home/.snap/snap1
           mount -o ro /dev/md0 /mnt/

     Delete a snapshot:

           rm /home/.snap/snap1

SEE ALSO

     rm(1), chmod(2), chown(8), mdconfig(8), mount(8), snapinfo(8)

HISTORY

     The mksnap_ffs utility first appeared in FreeBSD 5.1.

CAVEATS

     The disk full situation is not handled gracefully and may lead to a
     system panic when no free blocks are found.

     Every filesystem can have only up to 20 active snapshots.  When this
     limit is reached, attempting to create more snapshots fails with ENOSPC,
     and mksnap_ffs reports that it is "out of space".

FreeBSD 15.1-STABLE-HBSD         May 22, 2023                    MKSNAP_FFS(8)