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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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38 .Nd construct a new HAMMER file system
46 .Op Fl C Ar cachesize Ns Op Ns Cm \&: Ns Ar readahead
54 file system on device(s)
56 If multiple devices are specified a single
58 file system is created
59 which spans all of them.
62 will constitute a volume which the
64 file system is built on.
71 file systems are sector-size agnostic, however the
73 implementation requires the sector size to be no larger than 16KB.
75 file systems start at a relative offset of 0 and may only be created
76 under out-of-band disk labels
85 partitions which do not overlap the label area (have a starting sector
89 file systems are designed for large storage systems, up to 1 Exabyte, and
90 will not operate efficiently on small storage systems.
91 The minimum recommended file system size is 50GB.
93 must reserve 512MB to 1GB of its storage for reblocking and UNDO/REDO FIFO.
96 file systems operating normally, with full history
97 retention and daily snapshots, do not immediately reclaim space when
99 A regular system maintenance job runs once a day by
101 to handle reclamation.
104 works best when the machine's normal workload would not otherwise fill
105 the file system up in the course of 60 days of operation.
107 The options are as follows:
108 .Bl -tag -width indent
112 file systems must be named and names should be unique on a
113 per-machine basis, although
115 does not prevent from making file systems with the same label.
118 This is needed for the creation of a
120 file system less than 10GB size or
121 with less than 512MB UNDO/REDO FIFO.
122 This should not be used under normal circumstances.
124 Use TRIM to erase the device's data before creating the file system.
125 The underlying device must have the TRIM sysctl enabled.
126 Only devices that support TRIM will have such a sysctl option
127 .Va ( kern.cam.da.X.trim_enabled ) .
131 Specify a fixed area in which a boot related kernel and data can be stored.
132 This area is currently unused.
135 is specified in bytes with a suffix of
140 Specify a fixed area which
142 may use as a memory log.
143 This area is currently unused.
146 is specified in bytes with a suffix of
151 Specify the size of the fixed UNDO/REDO FIFO.
154 is specified in bytes with a suffix of
158 By default 0.1% of the root
159 volume's size is used, with a reasonable minimum and a reasonable cap.
160 The UNDO/REDO FIFO is used to sequence meta-data out to the media for
161 instant crash recovery.
162 .It Fl C Ar cachesize Ns Op Ns Cm \&: Ns Ar readahead
163 Refer to the same option in
168 file system version to format.
171 formats the file system using the highest production version number
175 .Va vfs.hammer.supported_version
177 If you need to maintain compatibility with an older version of
179 you may specify the version with this option.
187 must be given with a suffix of
191 meaning kilobyte, megabyte, gigabyte and terabyte.
192 Lower case can also be used for suffix.
196 Create a file system named
200 .Bd -literal -offset indent
201 newfs_hammer -L HOME /dev/ad0s1d
204 Create a file system named
210 .Bd -literal -offset indent
211 newfs_hammer -L TEMP /dev/ad0s1d /dev/ad1s1d
225 utility first appeared in
228 .An Matthew Dillon Aq Mt dillon@backplane.com