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4 .\" by Matthew Dillon <dillon@backplane.com>
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38 .Nd construct a new HAMMER file system
53 file system on device(s)
55 If multiple devices are specified a single
57 file system is created
58 which spans all of them.
61 will constitute a volume which the
63 file system is built on.
69 file systems are sector-size agnostic, however the
71 implementation requires the sector size to be no larger than 16K.
73 file systems start at a relative offset of 0 and may only be created
74 under out-of-band disk labels
83 partitions which do not overlap the label area (have a starting sector
87 file systems are designed for large storage systems, up to 1 Exabyte, and
88 will not operate efficiently on small storage systems.
89 The minimum recommended file system size is 50GB.
91 must reserve 500MB to 1GB of its storage for reblocking and UNDO/REDO.
94 file systems operating normally, with full history
95 retention and daily snapshots, do not immediately reclaim space when
97 A regular system maintenance job runs once a day by
99 to handle reclamation.
102 works best when the machine's normal workload would not otherwise fill
103 the file system up in the course of 60 days of operation.
105 The options are as follows:
106 .Bl -tag -width indent
110 file systems must be named and names should be unique on a
113 Specify a fixed area in which a boot related kernel and data can be stored.
116 is specified in bytes.
117 By default a boot area of approximately 4MB will be created.
120 This is needed for the creation of a
122 file system less than 10GB size or
123 with less than 500MB UNDO/REDO FIFO.
124 This should not be used under normal circumstances.
126 Use TRIM to erase the device's data before creating the file system.
127 The underlying device must have the TRIM sysctl enabled.
128 Only devices that support TRIM will have such a sysctl option
129 .Va ( kern.cam.da.X.trim_enabled ) .
131 Specify a fixed area which
133 may use as a memory log.
134 This area is currently unused.
137 is specified in bytes.
139 Specify the size of the fixed UNDO/REDO FIFO.
142 is specified in bytes.
143 By default 0.1% of the root
144 volume's size is used, with a reasonable minimum and a reasonable cap.
145 The UNDO/REDO FIFO is used to sequence meta-data out to the media for
146 instant crash recovery.
150 file system version to format.
153 formats the file system using the highest production version number
157 .Va vfs.hammer.supported_version
159 If you need to maintain compatibility with an older version of
161 you may specify the version with this option.
169 must be given with a suffix of
173 meaning kilobyte, megabyte, gigabyte and terabyte.
174 Lower case can also be used for suffix.
176 .Bd -literal -offset indent
177 newfs_hammer -L Home /dev/ad0s1d
180 Create a file system named
185 Exit status is 0 on success and 1 on error.
196 utility first appeared in
199 .An Matthew Dillon Aq Mt dillon@backplane.com