MOUNT_HAMMER(8) BSD System Manager's Manual MOUNT_HAMMER(8)NAMEmount_hammer — mount a HAMMER file system
SYNOPSISmount_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 sepa‐
rated 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 gener‐
ally 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 sup‐
port 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 dif‐
ferent 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.
EXAMPLES
Mount a HAMMER file system made up of two volumes onto /mnt:
mount_hammer-o ro,noatime /dev/ad0s1d /dev/ad1s1d /mnt
A corresponding fstab(5) entry is:
/dev/ad0s1d:/dev/ad1s1d /mnt hammer ro,noatime
DIAGNOSTICS
Exit status is 0 on success and 1 on error.
SEE ALSOmount(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⟩
BSD September 27, 2009 BSD
