tunefs(1M) System Administration Commands tunefs(1M)NAMEtunefs - tune an existing UFS file system
SYNOPSIStunefs [-a maxcontig] [-d rotdelay] [-e maxbpg] [-m minfree] [-o space
| time] special | filesystem
DESCRIPTIONtunefs is designed to change the dynamic parameters of a file system
that affect the layout policies. When using tunefs with filesystem,
filesystem must be in /etc/vfstab. The parameters that can be changed
are indicated by the options given below.
OPTIONS
The following options are supported:
-a maxcontig
The maximum number of logical blocks, belonging to one file, that
is allocated contiguously. The default is calculated as follows:
maxcontig = disk drive maximum transfer size / disk block size
If the disk drive's maximum transfer size cannot be determined, the
default value for maxcontig is calculated from kernel parameters as
follows:
If maxphys is less than ufs_maxmaxphys, which is 1 Mbyte, then max‐
contig is set to maxphys. Otherwise, maxcontig is set to ufs_max‐
maxphys.
You can set maxcontig to any positive integer value.
The actual value will be the lesser of what has been specified and
what the hardware supports.
-d rotdelay
This parameter is obsolete as of the Solaris 10 release. The value
is always set to 0, regardless of the input value.
-e maxbpg
Indicates the maximum number of contiguous logical blocks any sin‐
gle file can allocate from a cylinder group before it is forced to
begin allocating blocks from another cylinder group. Typically this
value is set to approximately one quarter of the total contiguous
logical blocks in a cylinder group. The intent is to prevent any
single file from using up all the blocks in a single cylinder
group, thus degrading access times for all files subsequently allo‐
cated in that cylinder group.
The effect of this limit is to cause big files to do long seeks
more frequently than if they were allowed to allocate all the
blocks in a cylinder group before seeking elsewhere. For file sys‐
tems with exclusively large files, this parameter should be set
higher.
-m minfree
Specifies the minimum free space threshold, or the percentage of
space held back from normal users. This value can be set to 0. How‐
ever, up to a factor of three in throughput will be lost over the
performance obtained at a 10% threshold. Note: If the value is
raised above the current usage level, users will be unable to allo‐
cate files until enough files have been deleted to get under the
higher threshold.
-o space|time
The file system can either be instructed to try to minimize the
time spent allocating blocks, or to try to minimize the space frag‐
mentation on the disk. The default is time.
Generally, you should optimize for time unless the file system is
over 90% full.
USAGE
See largefile(5) for the description of the behavior of tunefs when
encountering files greater than or equal to 2 Gbyte ( 2**31 bytes).
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWcsu │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOmkfs_ufs(1M), newfs(1M), attributes(5), largefile(5)SunOS 5.10 5 Dec 2003 tunefs(1M)
