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
Thenewfs_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:
-Llabel- All
HAMMERfile systems must be named and names should be unique on a per-machine basis, althoughnewfs_hammerdoes not prevent from making file systems with the same label. -f- Force operation. This is needed for the creation of a
HAMMERfile 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.
-bbootsize- 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,GorT. -msavesize- Specify a fixed area which
HAMMERmay use as a memory log. This area is currently unused. The savesize is specified in bytes with a suffix ofK,M,GorT. -uundosize- Specify the size of the fixed UNDO/REDO FIFO. The
undosize is specified in bytes with a suffix of
K,M,GorT. 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. -Ccachesize[:readahead]- Refer to the same option in hammer(8).
-Vversion- Specify the
HAMMERfile system version to format. By defaultnewfs_hammerformats the file system using the highest production version number supported by theHAMMERVFS by checking the vfs.hammer.supported_version sysctl. If you need to maintain compatibility with an older version ofHAMMERyou 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>