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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.
70 file systems are sector-size agnostic, however the
72 implementation requires the sector size to be no larger than 16KB.
74 file systems start at a relative offset of 0 and may only be created
75 under out-of-band disk labels
84 partitions which do not overlap the label area (have a starting sector
88 file systems are designed for large storage systems, up to 1 Exabyte, and
89 will not operate efficiently on small storage systems.
90 The minimum recommended file system size is 50GB.
92 must reserve 512MB to 1GB of its storage for reblocking and UNDO/REDO.
95 file systems operating normally, with full history
96 retention and daily snapshots, do not immediately reclaim space when
98 A regular system maintenance job runs once a day by
100 to handle reclamation.
103 works best when the machine's normal workload would not otherwise fill
104 the file system up in the course of 60 days of operation.
106 The options are as follows:
107 .Bl -tag -width indent
111 file systems must be named and names should be unique on a
112 per-machine basis, although
114 does not prevent from making file systems with the same label.
116 Specify a fixed area in which a boot related kernel and data can be stored.
117 This area is currently unused.
120 is specified in bytes.
123 This is needed for the creation of a
125 file system less than 10GB size or
126 with less than 512MB UNDO/REDO FIFO.
127 This should not be used under normal circumstances.
129 Use TRIM to erase the device's data before creating the file system.
130 The underlying device must have the TRIM sysctl enabled.
131 Only devices that support TRIM will have such a sysctl option
132 .Va ( kern.cam.da.X.trim_enabled ) .
134 Specify a fixed area which
136 may use as a memory log.
137 This area is currently unused.
140 is specified in bytes.
142 Specify the size of the fixed UNDO/REDO FIFO.
145 is specified in bytes.
146 By default 0.1% of the root
147 volume's size is used, with a reasonable minimum and a reasonable cap.
148 The UNDO/REDO FIFO is used to sequence meta-data out to the media for
149 instant crash recovery.
152 .It Fl C Ar cachesize Ns Op Ns Cm \&: Ns Ar readahead
153 Refer to the same option in
158 file system version to format.
161 formats the file system using the highest production version number
165 .Va vfs.hammer.supported_version
167 If you need to maintain compatibility with an older version of
169 you may specify the version with this option.
177 must be given with a suffix of
181 meaning kilobyte, megabyte, gigabyte and terabyte.
182 Lower case can also be used for suffix.
186 Create a file system named
190 .Bd -literal -offset indent
191 newfs_hammer -L HOME /dev/ad0s1d
194 Create a file system named
200 .Bd -literal -offset indent
201 newfs_hammer -L TEMP /dev/ad0s1d /dev/ad1s1d
215 utility first appeared in
218 .An Matthew Dillon Aq Mt dillon@backplane.com