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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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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
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.
65 file systems are sector-size agnostic, however the
67 implementation requires the sector size to be no larger than 16K.
69 file systems start at a relative offset of 0 and may only be created
70 under out-of-band disk labels
79 partitions which do not overlap the label area (have a starting sector
83 filesystems are designed for large storage systems, up to 1 Exabyte, and
84 will not operate efficiently on small storage systems.
85 The minimum recommended filesystem size is 50GB.
87 must reserve 500MB to 1GB of its storage for reblocking and UNDO.
88 In addition, HAMMER filesystems operating normally, with full history
89 retention and daily snapshots, do not immediately reclaim space when
90 files are deleted. A regular system maintainance cron job runs once
91 a day to handle reclamation.
94 works best when the machine's normal workload would not otherwise fill
95 the filesystem up in the course of 60 days of operation.
97 The options are as follows:
98 .Bl -tag -width indent
102 file systems must be named and names should be unique on a
105 Specify a fixed area in which a boot related kernel and data can be stored.
108 is specified in bytes.
109 By default a boot area of approximately 4MB will be created.
111 Force the creation of a
113 file system with less than 100M UNDO FIFO.
114 This should not be used under normal circumstances.
116 Specify a fixed area which
118 may use as a memory log.
119 This area is currently unused.
122 is specified in bytes.
124 Specify the size of the fixed UNDO FIFO.
127 is specified in bytes.
128 By default 0.1% of the root
129 volume's size is used, with a reasonable minimum and a reasonable cap.
130 The UNDO FIFO is used to sequence meta-data out to the media for instant
139 can be given with a suffix of
143 meaning kilo, mega, giga and tera. Lower case can also be used for suffix.
145 .Bd -literal -offset indent
146 newfs_hammer -L Home /dev/ad0s1d
149 Create a file system named
154 Exit status is 0 on success and 1 on error.
165 utility first appeared in
168 .An Matthew Dillon Aq dillon@backplane.com