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28 .\" @(#)newfs.8 8.6 (Berkeley) 5/3/95
36 .Nd construct a new UFS1/UFS2 file system
41 .Op Fl O Ar filesystem-type
42 .Op Fl S Ar sector-size
45 .Op Fl b Ar block-size
46 .Op Fl c Ar blocks-per-cylinder-group
47 .Op Fl d Ar max-extent-size
50 .Op Fl g Ar avgfilesize
53 .Op Fl k Ar held-for-metadata-blocks
54 .Op Fl m Ar free-space
55 .Op Fl o Ar optimization
63 utility is used to initialize and clear file systems before first use.
66 utility builds a file system on the specified special file.
67 (We often refer to the
71 although the special file need not be a physical disk.
72 In fact, it need not even be special.)
73 Typically the defaults are reasonable, however
75 has numerous options to allow the defaults to be selectively overridden.
77 The following options define the general layout policies:
78 .Bl -tag -width indent
80 Erase the content of the disk before making the filesystem.
81 The reserved area in front of the superblock (for bootcode) will not be erased.
83 This option is only relevant for flash based storage devices that use
84 wear-leveling algorithms.
86 Erasing may take a long time as it writes to every sector on the disk.
88 Enable journaling on the new file system via gjournal.
93 Add a volume label to the new file system.
94 Legal characters are alphanumerics and underscores.
96 Cause the file system parameters to be printed out
97 without really creating the file system.
98 .It Fl O Ar filesystem-type
99 Use 1 to specify that a UFS1 format file system be built;
100 use 2 to specify that a UFS2 format file system be built.
101 The default format is UFS2.
103 For backward compatibility.
105 Enable soft updates on the new file system.
106 .It Fl a Ar maxcontig
107 Specify the maximum number of contiguous blocks that will be
108 laid out before forcing a rotational delay.
109 The default value is 16.
112 for more details on how to set this option.
113 .It Fl b Ar block-size
114 The block size of the file system, in bytes.
115 It must be a power of 2.
117 default size is 32768 bytes, and the smallest allowable size is 4096 bytes.
118 The optimal block:fragment ratio is 8:1.
119 Other ratios are possible, but are not recommended,
120 and may produce poor results.
121 .It Fl c Ar blocks-per-cylinder-group
122 The number of blocks per cylinder group in a file system.
123 The default is to compute the maximum allowed by the other parameters.
125 dependent on a number of other parameters, in particular the block size
126 and the number of bytes per inode.
127 .It Fl d Ar max-extent-size
128 The file system may choose to store large files using extents.
129 This parameter specifies the largest extent size that may be used.
130 The default value is the file system blocksize.
131 It is presently limited to a maximum value of 16 times the
132 file system blocksize and a minimum value of the file system blocksize.
134 Indicate the maximum number of blocks any single file can
135 allocate out of a cylinder group before it is forced to begin
136 allocating blocks from another cylinder group.
137 The default is about one quarter of the total blocks in a cylinder group.
140 for more details on how to set this option.
141 .It Fl f Ar frag-size
142 The fragment size of the file system in bytes.
143 It must be a power of two
144 ranging in value between
148 The default is 4096 bytes.
149 .It Fl g Ar avgfilesize
150 The expected average file size for the file system.
152 The expected average number of files per directory on the file system.
154 Specify the density of inodes in the file system.
155 The default is to create an inode for every
158 If fewer inodes are desired, a larger number should be used;
159 to create more inodes a smaller number should be given.
160 One inode is required for each distinct file, so this value effectively
161 specifies the average file size on the file system.
163 Enable soft updates journaling on the new file system.
164 This flag is implemented by running the
166 utility found in the user's
168 .It Fl k Ar held-for-metadata-blocks
169 Set the amount of space to be held for metadata blocks in each cylinder group.
170 When set, the file system preference routines will try to save
171 the specified amount of space immediately following the inode blocks
172 in each cylinder group for use by metadata blocks.
173 Clustering the metadata blocks speeds up random file access
174 and decreases the running time of
178 sets it to half of the space reserved to minfree.
180 Enable multilabel MAC on the new file system.
181 .It Fl m Ar free-space
182 The percentage of space reserved from normal users; the minimum free
184 The default value used is
192 for more details on how to set this option.
196 directory on the new file system.
197 The resulting file system will not support snapshot generation, so
199 in live mode and background
201 will not function properly.
206 will work on the file system.
207 This option is intended primarily for memory or vnode-backed file systems that
213 .It Fl o Ar optimization
217 The file system can either be instructed to try to minimize the time spent
218 allocating blocks, or to try to minimize the space fragmentation on the disk.
219 If the value of minfree (see above) is less than 8%,
220 the default is to optimize for
222 if the value of minfree is greater than or equal to 8%,
223 the default is to optimize for
227 for more details on how to set this option.
228 .It Fl p Ar partition
229 The partition name (a..h) you want to use in case the underlying image
230 is a file, so you do not have access to individual partitions through the
232 Can also be used with a device, e.g.,
240 The size, in sectors, of reserved space
241 at the end of the partition specified in
243 This space will not be occupied by the file system;
244 it can be used by other consumers such as
248 The size of the file system in sectors.
249 This value defaults to the size of the
250 raw partition specified in
254 space at its end (see
258 of 0 can also be used to choose the default value.
261 value cannot be larger than the default one,
262 which means that the file system cannot extend into the reserved space.
264 Turn on the TRIM enable flag.
265 If enabled, and if the underlying device supports the BIO_DELETE
266 command, the file system will send a delete request to the underlying
267 device for each freed block.
268 The trim enable flag is typically set when the underlying device
269 uses flash-memory as the device can use the delete command to
270 pre-zero or at least avoid copying blocks that have been deleted.
273 The following options override the standard sizes for the disk geometry.
274 Their default values are taken from the disk label.
275 Changing these defaults is useful only when using
277 to build a file system whose raw image will eventually be used on a
278 different type of disk than the one on which it is initially created
279 (for example on a write-once disk).
280 Note that changing any of these values from their defaults will make
283 to find the alternate superblocks if the standard superblock is lost.
284 .Bl -tag -width indent
285 .It Fl S Ar sector-size
286 The size of a sector in bytes (almost never anything but 512).
289 .Dl newfs /dev/ada3s1a
291 Creates a new ufs file system on
295 utility will use a block size of 32768 bytes, a fragment size of 4096 bytes
296 and the largest possible number of blocks per cylinders group.
297 These values tend to produce better performance for most applications
298 than the historical defaults
299 (8192 byte block size and 1024 byte fragment size).
300 This large fragment size may lead to much wasted space
301 on file systems that contain many small files.
323 .%T A Fast File System for UNIX
324 .%J ACM Transactions on Computer Systems 2
328 .%O (reprinted in the BSD System Manager's Manual)