1tunefs(1M) System Administration Commands tunefs(1M)
2
6 tunefs - tune an existing UFS file system
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9 tunefs [-a maxcontig] [-d rotdelay] [-e maxbpg]
10 [-m minfree] [-o space | time] special | filesystem
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14 tunefs is designed to change the dynamic parameters of a file system
15 that affect the layout policies. When using tunefs with filesystem,
16 filesystem must be in /etc/vfstab. The parameters that can be changed
17 are indicated by the options given below.
18
20 The following options are supported:
21 -a maxcontig The maximum number of logical blocks, belonging to
23 one file, that is allocated contiguously. The
24 default is calculated as follows:
25 maxcontig = disk drive maximum transfer size / disk block size
27 If the disk drive's maximum transfer size cannot
30 be determined, the default value for maxcontig is
31 calculated from kernel parameters as follows:
32 If maxphys is less than ufs_maxmaxphys, which is 1
34 Mbyte, then maxcontig is set to maxphys. Other‐
35 wise, maxcontig is set to ufs_maxmaxphys.
36 You can set maxcontig to any positive integer
38 value.
39 The actual value will be the lesser of what has
41 been specified and what the hardware supports.
42 -d rotdelay This parameter is obsolete as of the Solaris 10
45 release. The value is always set to 0, regardless
46 of the input value.
47 -e maxbpg Indicates the maximum number of contiguous logical
50 blocks any single file can allocate from a cylin‐
51 der group before it is forced to begin allocating
52 blocks from another cylinder group. Typically this
53 value is set to approximately one quarter of the
54 total contiguous logical blocks in a cylinder
55 group. The intent is to prevent any single file
56 from using up all the blocks in a single cylinder
57 group, thus degrading access times for all files
58 subsequently allocated in that cylinder group.
59 The effect of this limit is to cause big files to
61 do long seeks more frequently than if they were
62 allowed to allocate all the blocks in a cylinder
63 group before seeking elsewhere. For file systems
64 with exclusively large files, this parameter
65 should be set higher.
66 -m minfree Specifies the minimum free space threshold, or the
69 percentage of space held back from normal users.
70 This value can be set to 0. However, up to a fac‐
71 tor of three in throughput will be lost over the
72 performance obtained at a 10% threshold. Note: If
73 the value is raised above the current usage level,
74 users will be unable to allocate files until
75 enough files have been deleted to get under the
76 higher threshold.
77 -o space|time The file system can either be instructed to try to
80 minimize the time spent allocating blocks, or to
81 try to minimize the space fragmentation on the
82 disk. The default is time.
83 Generally, you should optimize for time unless the
85 file system is over 90% full.
86
89 See largefile(5) for the description of the behavior of tunefs when
90 encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).
91
93 See attributes(5) for descriptions of the following attributes:
94 ┌─────────────────────────────┬─────────────────────────────┐
99 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
100 ├─────────────────────────────┼─────────────────────────────┤
101 │Availability │SUNWcsu │
102 └─────────────────────────────┴─────────────────────────────┘
103
105 mkfs_ufs(1M), newfs(1M), attributes(5), largefile(5)
106SunOS 5.11 5 Dec 2003 tunefs(1M)