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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 $
39 .Nd construct a new HAMMER file system
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.
66 file systems are sector-size agnostic, however the
68 implementation requires the sector size to be no larger than 16K.
70 file systems start at a relative offset of 0 and may only be created
71 under out-of-band disk labels
80 partitions which do not overlap the label area (have a starting sector
84 file systems are designed for large storage systems, up to 1 Exabyte, and
85 will not operate efficiently on small storage systems.
86 The minimum recommended file system size is 50GB.
88 must reserve 500MB to 1GB of its storage for reblocking and UNDO/REDO.
91 file systems operating normally, with full history
92 retention and daily snapshots, do not immediately reclaim space when
94 A regular system maintenance job runs once a day by
96 to handle reclamation.
99 works best when the machine's normal workload would not otherwise fill
100 the file system up in the course of 60 days of operation.
102 The options are as follows:
103 .Bl -tag -width indent
107 file systems must be named and names should be unique on a
110 Specify a fixed area in which a boot related kernel and data can be stored.
113 is specified in bytes.
114 By default a boot area of approximately 4MB will be created.
117 This is needed for the creation of a
119 file system less than 10GB size or
120 with less than 500MB UNDO/REDO FIFO.
121 This should not be used under normal circumstances.
123 Use TRIM to erase the device's data before creating the file system. The
124 underlying device must have the Trim sysctl enabled. Only devices that support
125 TRIM will have such a sysctl option (kern.cam.da.X.trim_enabled).
127 Specify a fixed area which
129 may use as a memory log.
130 This area is currently unused.
133 is specified in bytes.
135 Specify the size of the fixed UNDO/REDO FIFO.
138 is specified in bytes.
139 By default 0.1% of the root
140 volume's size is used, with a reasonable minimum and a reasonable cap.
141 The UNDO/REDO FIFO is used to sequence meta-data out to the media for
142 instant crash recovery.
146 file system version to format.
149 formats the file system using the highest production version number
153 .Va vfs.hammer.supported_version
155 If you need to maintain compatibility with an older version of
157 you may specify the version with this option.
165 must be given with a suffix of
169 meaning kilobyte, megabyte, gigabyte and terabyte.
170 Lower case can also be used for suffix.
172 .Bd -literal -offset indent
173 newfs_hammer -L Home /dev/ad0s1d
176 Create a file system named
181 Exit status is 0 on success and 1 on error.
192 utility first appeared in
195 .An Matthew Dillon Aq dillon@backplane.com