1.\" Copyright (c) 2007 The DragonFly Project.  All rights reserved.
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3.\" This code is derived from software contributed to The DragonFly Project
4.\" by Matthew Dillon <dillon@backplane.com>
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33.\" $DragonFly: src/sbin/newfs_hammer/newfs_hammer.8,v 1.10 2008/07/27 16:47:19 thomas Exp $
34.Dd July 24, 2008
35.Dt NEWFS_HAMMER 8
36.Os
37.Sh NAME
38.Nm newfs_hammer
39.Nd construct a new HAMMER file system
40.Sh SYNOPSIS
41.Nm
42.Fl L Ar label
43.Op Fl b Ar bootsize
44.Op Fl f
45.Op Fl m Ar savesize
46.Op Fl u Ar undosize
47.Op Fl V Ar version
48.Ar special ...
49.Sh DESCRIPTION
50The
51.Nm
52utility creates a
53.Nm HAMMER
54file system on device
55.Ar special .
56If multiple devices are specified a single
57.Nm HAMMER
58file system is created
59which spans all of them.
60Each
61.Ar special
62will constitute a volume which the
63.Nm HAMMER
64file system is built on.
65.Nm HAMMER
66file systems are sector-size agnostic, however the
67.Dx
68implementation requires the sector size to be no larger than 16K.
69.Nm HAMMER
70file systems start at a relative offset of 0 and may only be created
71under out-of-band disk labels
72.Po
73.Xr disklabel64 5
74or
75.Xr gpt 8
76labels
77.Pc ,
78or in
79.Xr disklabel 5
80partitions which do not overlap the label area (have a starting sector
81greater then 16).
82.Pp
83.Nm HAMMER
84filesystems are designed for large storage systems, up to 1 Exabyte, and
85will not operate efficiently on small storage systems.
86The minimum recommended filesystem size is 50GB.
87.Nm HAMMER
88must reserve 500MB to 1GB of its storage for reblocking and UNDO.
89In addition, HAMMER filesystems operating normally, with full history
90retention and daily snapshots, do not immediately reclaim space when
91files are deleted.
92A regular system maintenance cron job runs once a day to handle reclamation.
93.Pp
94.Nm HAMMER
95works best when the machine's normal workload would not otherwise fill
96the filesystem up in the course of 60 days of operation.
97.Pp
98The options are as follows:
99.Bl -tag -width indent
100.It Fl L Ar label
101All
102.Nm HAMMER
103file systems must be named and names should be unique on a
104per-machine basis.
105.It Fl b Ar bootsize
106Specify a fixed area in which a boot related kernel and data can be stored.
107The
108.Ar bootsize
109is specified in bytes.
110By default a boot area of approximately 4MB will be created.
111.It Fl f
112Force the creation of a
113.Nm HAMMER
114file system with less than 100M UNDO FIFO.
115This should not be used under normal circumstances.
116.It Fl m Ar savesize
117Specify a fixed area which
118.Nm HAMMER
119may use as a memory log.
120This area is currently unused.
121The
122.Ar savesize
123is specified in bytes.
124.It Fl u Ar undosize
125Specify the size of the fixed UNDO FIFO.
126The
127.Ar undosize
128is specified in bytes.
129By default 0.1% of the root
130volume's size is used, with a reasonable minimum and a reasonable cap.
131The UNDO FIFO is used to sequence meta-data out to the media for instant
132crash recovery.
133.It Fl V Ar version
134Specify the HAMMER filesystem version to format.
135By default
136.Nm
137formats the filesystem using the highest production version number
138supported by the HAMMER VFS by checking the vfs.hammer.supported_version
139sysctl.
140If you need to maintain compatibility with an older version of HAMMER
141you may specify the version with this option.
142.El
143.Pp
144The
145.Ar bootsize ,
146.Ar savesize
147and
148.Ar undosize
149can be given with a suffix of
150.Cm K , M , G
151or
152.Cm T
153meaning kilo, mega, giga and tera.
154Lower case can also be used for suffix.
155.Sh EXAMPLES
156.Bd -literal -offset indent
157newfs_hammer -L Home /dev/ad0s1d
158.Ed
159.Pp
160Create a file system named
161.Sq Home
162on
163.Pa /dev/ad0s1d .
164.Sh DIAGNOSTICS
165Exit status is 0 on success and 1 on error.
166.Sh SEE ALSO
167.Xr disklabel 5 ,
168.Xr disklabel64 5 ,
169.Xr HAMMER 5 ,
170.Xr fdisk 8 ,
171.Xr gpt 8 ,
172.Xr newfs 8
173.Sh HISTORY
174The
175.Nm
176utility first appeared in
177.Dx 1.11 .
178.Sh AUTHORS
179.An Matthew Dillon Aq dillon@backplane.com
180