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
Themount_hammer utility mounts a
HAMMER file system backed by
special file(s) at mount point
node.
The options are as follows:
-ooptions- Options are specified with a
-oflag followed by a comma separated string of options. See the mount(8) man page for possible options and their meanings. The followingHAMMERspecific 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
HAMMERmounts making up the fail-over group. nomirror- By default a
HAMMERmount 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.
-Ttransaction-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>