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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
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 16KB.
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
111 per-machine basis, although
113 does not prevent from making file systems with the same label.
115 Specify a fixed area in which a boot related kernel and data can be stored.
116 This area is currently unused.
119 is specified in bytes.
122 This is needed for the creation of a
124 file system less than 10GB size or
125 with less than 500MB UNDO/REDO FIFO.
126 This should not be used under normal circumstances.
128 Use TRIM to erase the device's data before creating the file system.
129 The underlying device must have the TRIM sysctl enabled.
130 Only devices that support TRIM will have such a sysctl option
131 .Va ( kern.cam.da.X.trim_enabled ) .
133 Specify a fixed area which
135 may use as a memory log.
136 This area is currently unused.
139 is specified in bytes.
141 Specify the size of the fixed UNDO/REDO FIFO.
144 is specified in bytes.
145 By default 0.1% of the root
146 volume's size is used, with a reasonable minimum and a reasonable cap.
147 The UNDO/REDO FIFO is used to sequence meta-data out to the media for
148 instant crash recovery.
152 file system version to format.
155 formats the file system using the highest production version number
159 .Va vfs.hammer.supported_version
161 If you need to maintain compatibility with an older version of
163 you may specify the version with this option.
171 must be given with a suffix of
175 meaning kilobyte, megabyte, gigabyte and terabyte.
176 Lower case can also be used for suffix.
180 Create a file system named
184 .Bd -literal -offset indent
185 newfs_hammer -L HOME /dev/ad0s1d
188 Create a file system named
194 .Bd -literal -offset indent
195 newfs_hammer -L TEMP /dev/ad0s1d /dev/ad1s1d
209 utility first appeared in
212 .An Matthew Dillon Aq Mt dillon@backplane.com