tunefs(1M_SFS)                 (SFS)                  tunefs(1M_SFS)


       NAME
             tunefs (sfs) - tune up an existing file system

       SYNOPSIS
             tunefs [-a maxcontig] [-d rotdelay] [-e maxbpg]
                   [-o [s | space | t | time]] special | filesystem

       DESCRIPTION
             tunefs is designed to change the dynamic parameters of a file
             system which affect the layout policies.  The file system must
             be unmounted before using tunefs.  The parameters which are to
             be changed are indicated by the options given below:

             The options are:

            -a maxcontig
                     Specify the maximum number of contiguous blocks that
                     will be laid out before forcing a rotational delay
                     (see -d below).  The default value is one, since most
                     device drivers require an interrupt per disk transfer.
                     Device drivers that can chain several buffers together
                     in a single transfer should set this to the maximum
                     chain length.

            -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
                     approximately 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 frequently 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.


                           Copyright 1994 Novell, Inc.               Page 1

      tunefs(1M_SFS)                 (SFS)                  tunefs(1M_SFS)


           -o [s | space | t | time]
                    Change optimization strategy for the file system.  s
                    and space are interchangeable, and t and time are
                    interchangeable.

                    s or space    Conserve space.

                    t or time     Organize file layout to minimize access
                                  time.

                   Generally one should optimize for time unless the file
                    system is over 90% full.

      NOTICES
            The tunable minfree is not supported on sfs file systems.

      REFERENCES
            fork(2), sfs-specific fs(4SFS), mkfs(1M), terminfo(4)






























                          Copyright 1994 Novell, Inc.               Page 2