.\" Copyright (c) 2007 The DragonFly Project.  All rights reserved.
.\" 
.\" This code is derived from software contributed to The DragonFly Project
.\" by Matthew Dillon <dillon@backplane.com>
.\" 
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.\" $DragonFly: src/sbin/newfs_hammer/newfs_hammer.8,v 1.10 2008/07/27 16:47:19 thomas Exp $
.Dd July 24, 2008
.Dt NEWFS_HAMMER 8
.Os
.Sh NAME
.Nm newfs_hammer
.Nd construct a new HAMMER file system
.Sh SYNOPSIS
.Nm
.Fl L Ar label
.Op Fl b Ar bootsize
.Op Fl f
.Op Fl m Ar savesize
.Op Fl u Ar undosize
.Ar special ...
.Sh DESCRIPTION
The
.Nm
utility creates a
.Nm HAMMER
file system on device
.Ar special .
If multiple devices are specified a single
.Nm HAMMER
file system is created
which spans all of them.
Each
.Ar special
will constitute a volume which the
.Nm HAMMER
file system is built on.
.Nm HAMMER
file systems are sector-size agnostic, however the
.Dx
implementation requires the sector size to be no larger than 16K.
.Nm HAMMER
file systems start at a relative offset of 0 and may only be created
under out-of-band disk labels
.Po
.Xr disklabel64 5
or
.Xr gpt 8
labels
.Pc ,
or in
.Xr disklabel 5
partitions which do not overlap the label area.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl L Ar label
All
.Nm HAMMER
file systems must be named and names should be unique on a
per-machine basis.
.It Fl b Ar bootsize
Specify a fixed area in which a boot related kernel and data can be stored.
The
.Ar bootsize
is specified in bytes.
By default a boot area of approximately 4MB will be created.
.It Fl f
Force the creation of a
.Nm HAMMER
file system with less than 100M UNDO FIFO.
This should not be used under normal circumstances.
.It Fl m Ar savesize
Specify a fixed area which
.Nm HAMMER
may use as a memory log.
This area is currently unused.
The
.Ar savesize
is specified in bytes.
.It Fl u Ar undosize
Specify the size of the fixed UNDO FIFO.
The
.Ar undosize
is specified in bytes.
By default 0.1% of the root
volume's size is used, with a reasonable minimum and a reasonable cap.
The UNDO FIFO is used to sequence meta-data out to the media for instant
crash recovery.
.El
.Pp
The
.Ar bootsize ,
.Ar savesize
and
.Ar undosize
can be given with a suffix of
.Cm K , M , G
or
.Cm T
meaning kilo, mega, giga and tera. Lower case can also be used for suffix.
.Sh EXAMPLES
.Bd -literal -offset indent
newfs_hammer -L Home /dev/ad0s1d
.Ed
.Pp
Create a file system named
.Sq Home
on
.Pa /dev/ad0s1d .
.Sh DIAGNOSTICS
Exit status is 0 on success and 1 on error.
.Sh SEE ALSO
.Xr disklabel 5 ,
.Xr disklabel64 5 ,
.Xr HAMMER 5 ,
.Xr fdisk 8 ,
.Xr gpt 8 ,
.Xr newfs 8
.Sh HISTORY
The
.Nm
utility first appeared in
.Dx 1.11 .
.Sh AUTHORS
.An Matthew Dillon Aq dillon@backplane.com