DragonFly On-Line Manual Pages

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

NAME
     newfs_hammer -- construct a new HAMMER file system

SYNOPSIS
     newfs_hammer -L label [-Efh] [-b bootsize] [-m savesize] [-u undosize]
                  [-C cachesize[:readahead]] [-V version] special ...

DESCRIPTION
     The newfs_hammer utility creates a HAMMER file system on device(s)
     special.  If multiple devices are specified a single HAMMER file system
     is created which spans all of them.  Each special will constitute a
     volume which the HAMMER file system is built on.  The first special
     specified becomes the root-volume with volume# 0.  HAMMER file systems
     are sector-size agnostic, however the DragonFly implementation requires
     the sector size to be no larger than 16KB.  HAMMER file systems start at
     a relative offset of 0 and may only be created under out-of-band disk
     labels (disklabel64(5) or gpt(8) labels), or in disklabel32(5) partitions
     which do not overlap the label area (have a starting sector greater than
     16).

     HAMMER file systems are designed for large storage systems, up to 1
     Exabyte, and will not operate efficiently on small storage systems.  The
     minimum recommended file system size is 50GB.  HAMMER must reserve 512MB
     to 1GB of its storage for reblocking and UNDO/REDO FIFO.  In addition,
     HAMMER file systems operating normally, with full history retention and
     daily snapshots, do not immediately reclaim space when files are deleted.
     A regular system maintenance job runs once a day by periodic(8) to handle
     reclamation.

     HAMMER works best when the machine's normal workload would not otherwise
     fill the file system up in the course of 60 days of operation.

     The options are as follows:

     -L label
             All HAMMER file systems must be named and names should be unique
             on a per-machine basis, although newfs_hammer does not prevent
             from making file systems with the same label.

     -f      Force operation.  This is needed for the creation of a HAMMER
             file system less than 10GB size or with less than 512MB UNDO/REDO
             FIFO.  This should not be used under normal circumstances.

     -E      Use TRIM to erase the device's data before creating the file
             system.  The underlying device must have the TRIM sysctl enabled.
             Only devices that support TRIM will have such a sysctl option
             (kern.cam.da.X.trim_enabled).

     -h      Show usage.

     -b bootsize
             Specify a fixed area in which a boot related kernel and data can
             be stored.  This area is currently unused.  The bootsize is
             specified in bytes with a suffix of K, M, G or T.

     -m savesize
             Specify a fixed area which HAMMER may use as a memory log.  This
             area is currently unused.  The savesize is specified in bytes
             with a suffix of K, M, G or T.

     -u undosize
             Specify the size of the fixed UNDO/REDO FIFO.  The undosize is
             specified in bytes with a suffix of K, M, G or T.  By default
             0.1% of the root volume's size is used, with a reasonable minimum
             and a reasonable cap.  The UNDO/REDO FIFO is used to sequence
             meta-data out to the media for instant crash recovery.

     -C cachesize[:readahead]
             Refer to the same option in hammer(8).

     -V version
             Specify the HAMMER file system version to format.  By default
             newfs_hammer formats the file system using the highest production
             version number supported by the HAMMER VFS by checking the
             vfs.hammer.supported_version sysctl.  If you need to maintain
             compatibility with an older version of HAMMER you may specify the
             version with this option.

     The bootsize, savesize and undosize must be given with a suffix of K, M,
     G or T meaning kilobyte, megabyte, gigabyte and terabyte.  Lower case can
     also be used for suffix.

EXIT STATUS
     The newfs_hammer utility exits 0 on success, and >0 if an error occurs.

EXAMPLES
     Create a file system named `HOME' on /dev/ad0s1d:

           newfs_hammer -L HOME /dev/ad0s1d

     Create a file system named `TEMP' on /dev/ad0s1d and /dev/ad1s1d:

           newfs_hammer -L TEMP /dev/ad0s1d /dev/ad1s1d

SEE ALSO
     disklabel32(5), disklabel64(5), HAMMER(5), fdisk(8), gpt(8), hammer(8),
     mount_hammer(8), newfs(8)

HISTORY
     The newfs_hammer utility first appeared in DragonFly 1.11.

AUTHORS
     Matthew Dillon <dillon@backplane.com>

DragonFly 4.7                  December 16, 2016                 DragonFly 4.7