tunefs

 

---

 
 
 
 Maintenance Commands                                   tunefs(1M)
 
 
 


NAME
      tunefs - tune up an existing 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  which  affect  the layout policies. When using
      tunefs with  filesystem, filesystem must be in  /etc/vfstab.
      The  parameters which are to be changed are indicated by the
      options given below.
 
      Generally one should optimize for time unless the file  sys-
      tem is over 90% full.
 


OPTIONS
      -a maxcontig
            Specify the maximum number of contiguous  blocks  that
            will  be  laid  out  before forcing a rotational delay
            (see -d). The default value  is  determined  from  the
            disk  drive's  maximum transfer rate. The maximum max-
            config that UFS supports is 10486576.
 
      -d rotdelay
            Specify the expected time (in milliseconds) to service
            a  transfer  completion  interrupt  and initiate a new
            transfer on the same disk. It is used  to  decide  how
            much  rotational  spacing  to place between successive
            blocks in a file.
 
      -e maxbpg
            Indicate the maximum number of blocks any single  file
            can  allocate  out  of  a  cylinder group before it is
            forced  to  begin  allocating  blocks   from   another
            cylinder group. Typically this value is set to approx-
            imately one quarter of the total 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
            Specify the percentage of space held back from  normal
            users;  the  minimum  free space threshold. This value
 
 
 
 SunOS 5.8           Last change: 18 Feb 1999                    1
 
 
 
 
 
 
 Maintenance Commands                                   tunefs(1M)
 
 
 
            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[space|time]
            Change optimization strategy for the file system.
 
            space: conserve space
 
            time: attempt to  organize  file  layout  to  minimize
            access time
 
 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  attri-
      butes:
 
      ____________________________________________________________
     |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
     |_____________________________|_____________________________|
     | Availability                | SUNWcsu                     |
     |_____________________________|_____________________________|
 
 


SEE ALSO
      mkfs(1M), fork(2), terminfo(4), attributes(5), largefile(5)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 SunOS 5.8           Last change: 18 Feb 1999                    2
 
 
 

---