.\" 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 1.6 2008/04/27 00:43:57 dillon Exp $
.Dd September 10, 2007
.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 m Ar savesize
.Op Fl u Ar undosize
.Ar special ...
.Sh DESCRIPTION
The
.Nm
utility creates a HAMMER filesystem on device
.Ar special .
If multiple devices are specified a single HAMMER filesystem is created
which spans all of them.
HAMMER filesystems are sector-size agnostic, however the
.Dx
implementation requires the sector size to be no larger than 16K.
HAMMER filesystems start at a relative offset of 0 and may only be created
under out-of-band disk labels (disklabel64 or gpt labels), or in standard
disklabel partitions which do not overlap the label area.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl L Ar label
All HAMMER filesystems 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.
By default a boot area of approximately 4MB will be created.
.It Fl m Ar savesize
Specify a fixed area which HAMMER may use as a memory log.  This area is
currently unused.
.It Fl u Ar undosize
Specify the size of the fixed UNDO FIFO.  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
.\".Sh NOTES
.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 8 ,
.Xr fdisk 8 ,
.Xr newfs 8
.Sh HISTORY
The
.Nm
utility first appeared in
.Dx 1.11 .
.Sh AUTHORS
.An Matthew Dillon Aq dillon@backplane.com