DragonFly On-Line Manual Pages

Search: Section:  

MOUNT_HAMMER(8)        DragonFly System Manager's Manual       MOUNT_HAMMER(8)


NAME

     mount_hammer -- mount a HAMMER file system


SYNOPSIS

     mount_hammer [-o options] [-T transaction-id] special ... node
     mount_hammer [-o options] [-T transaction-id] special[:special]* node
     mount_hammer -u [-o options] node


DESCRIPTION

     The mount_hammer utility mounts a HAMMER file system backed by special
     file(s) at mount point node.

     The options are as follows:

     -o options
             Options are specified with a -o flag followed by a comma
             separated string of options.  See the mount(8) man page for
             possible options and their meanings.  The following HAMMER
             specific options are also available:

             nohistory
                     Put the entire file system in no-history mode.  Change
                     history is not retained.  Use of this option may increase
                     the overhead of doing mirroring.  This option is
                     generally only used in an emergency.

             master=id
                     Assign a master id for the entire mount which applies to
                     all PFSs under the mount.  This is intended to help
                     support multi-master and fail-over operation.  Multi-
                     master operation is not yet supported.  If you intend to
                     upgrade slaves to masters and downgrade masters to slaves
                     as part of a fail-over setup, it's a good idea to assign
                     a different master id to the HAMMER mounts making up the
                     fail-over group.

             nomirror
                     By default a HAMMER mount assigns a master id of 0.  You
                     can force no-mirror operation by specifying this option.
                     This option disables mirror transaction id propagation in
                     the B-Tree and will improve write performance somewhat
                     but also prevents incremental mirroring from working at
                     all, and is not recommended.

     -T transaction-id
             Mount the file system as-of a particular transaction id.  The
             mount will automatically be made read-only.  The transaction-id
             must be specified as a 64 bit hex value prefixed with "0x".

     -u      Update the mount point.  This is typically used to upgrade a
             mount to read-write or downgrade it to read-only.


NOTES

     Note that issuing a read-only mount which requires UNDOs to be run will
     still run the UNDOs, but will not flush the buffer cache buffers until/if
     the mount is updated to read-write.


EXIT STATUS

     The mount_hammer utility exits 0 on success, and >0 if an error occurs.


EXAMPLES

     Mount a HAMMER file system made up of two volumes onto /mnt:

           mount_hammer -o ro,noatime /dev/ad0s1d /dev/ad1s1d /mnt

     Above is equivalent to below using blkdevs format for HAMMER volumes as
     mount_hammer supports both formats.

           mount_hammer -o ro,noatime /dev/ad0s1d:/dev/ad1s1d /mnt

     A corresponding fstab(5) entry is:

           /dev/ad0s1d:/dev/ad1s1d /mnt hammer ro,noatime


SEE ALSO

     mount(2), unmount(2), fstab(5), HAMMER(5), disklabel(8), disklabel64(8),
     fdisk(8), gpt(8), hammer(8), mount(8), newfs_hammer(8)


HISTORY

     The mount_hammer utility first appeared in DragonFly 1.11.


AUTHORS

     Matthew Dillon <dillon@backplane.com>

DragonFly 4.3                  December 31, 2015                 DragonFly 4.3

Search: Section: