System Administration Commands tunefs(1M)
NAME
tunefs - tune an existing UFS file system
SYNOPSIS
tunefs [-a maxcontig] [-d rotdelay] [-e maxbpg]
[-m minfree] [-o space time] special filesystem
DESCRIPTION
tunefs 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 allo-
cated contiguously. The default is cal-
culated 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 ufsmaxmaxphys,
which is 1 Mbyte, then maxcontig is set
to maxphys. Otherwise, maxcontig is set
to ufsmaxmaxphys.
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-d rotdelay This parameter is obsolete as of the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 con-
tiguous logical blocks any single file
SunOS 5.11 Last change: 5 Dec 2003 1
System Administration Commands tunefs(1M)
can allocate from a cylinder group
before it is forced to begin allocating
blocks from another cylinder group.
Typically this value is set to approxi-
mately one quarter of the total con-
tiguous 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 allocated in that cylinder
group.
The effect of this limit is to cause
big files to do long seeks more fre-
quently than if they were allowed to
allocate all the blocks in a cylinder
group before seeking elsewhere. For
file systems with exclusively large
files, this parameter should be set
higher.
-m minfree Specifies the minimum free space thres-
hold, or the percentage of space held
back from normal users. This value can
be set to 0. However, 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 allocate files until
enough files have been deleted to get
under the higher threshold.
-o spacetime The file system can either be
instructed to try to minimize the time
spent allocating blocks, or to try to
minimize the space fragmentation 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).
SunOS 5.11 Last change: 5 Dec 2003 2
System Administration Commands tunefs(1M)
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcsu
SEE ALSO
mkfsufs(1M), newfs(1M), attributes(5), largefile(5)
SunOS 5.11 Last change: 5 Dec 2003 3
|
