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.

     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 /usr/home file system and mount the snapshot
     elsewhere:

           mksnap_ffs /usr/home/snapshot
           mdconfig -a -t vnode -o readonly -f /usr/home/snapshot
           mount -o ro /dev/md0 /mnt/

SEE ALSO
     chmod(2), chown(8), mdconfig(8), mount(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 13.1-RELEASE-p6         October 3, 2016        FreeBSD 13.1-RELEASE-p6