dktune(8)                                                         dktune(8)

NAME
     dktune - read/write disk tuning information

SYNOPSIS
     dktune -l pathname

     dktune -d [-wv] pathname

     dktune -t [-wv] tunefile pathname

     dktune [-wv] pathname < tunefile

DESCRIPTION
     The dktune utility is used to initialize, update or display the dktune
     structure in the PSDF [Pyramid Standard Disk Format - see psdf(4)].
     dktune is normally called with a tuning structure supplied by Pyramid,
     prior to formatting a new disk.

     After formatting, dktune may be used to change or display the tuning
     structure.

     Tuning data structures are files stored in
     /etc/default/diskinfo/dktune/*.

OPTIONS
     -d   Sets the disk tuning to a generic default (for example, no disk
          tuning and little optimization).

     -l   Lists tuning parameters from the disk.

     -v   Lists tuning parameters after setting.

     -w   Does not attempt to write the tuning structure on disk.

     -t tunefile
          Sets the disk tuning as specified in tunefile. If tunefile con-
          tains a "/", dktune tries to open tunefile, otherwise dktune
          opens tunefile in the directory /etc/default/diskinfo/dktune.

     pathname
          Device path name.














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dktune(8)                                                         dktune(8)

EXAMPLES
     Use the following to display the tuning data from the PSDF for disk
     /dev/ios/sdisk000s0:

          dktune -l /dev/ios/rsdisk000s0

     The output is in the dktune source format:

     #
     #dktune for /dev/ios0/rsdisk000s0
     #
               dkuflags='DKUELEVATOR'
             dkutrkskew=13       # physical head skew
             dkucylskew=21       # physical cylinder skew
              dkurotgap=8        # rotational gap between all requests
              dkutrkgap=0        # rotational gap on track switches
              dkucylgap=0        # linear disk head acceleration on seeks
            dkurotdelay=2        # file system rotational delay in milliseconds
            dkuvelocity=0        # max linear disk head velocity on seeks
        dkutimeouthigh=500000   # IOhigh priority queue timeout
        dkutimeoutnorm=700000   # IOnormal priority queue timeout
         dkutimeoutlow=1000000  # IOlow priority queue timeout
         dkutimeoutord=0        # IOordered priority queue timeout

     Use the following to initialize or update PSDF on /dev/ios0/sdisk000
     with the dktune data from /etc/default/diskinfo/dktune/HP97536:

          dktune -t HP97536 /dev/ios0/rsdisk000s0

     To initialize or update PSDF on /dev/ios0/sdisk000 with the default
     tuning structure:

          dktune -d /dev/ios0/rsdisk000s0

NOTE
     It is better to specify default (no) tuning than to load incorrect
     tuning data.

FILES
     /etc/default/diskinfo/dktune/*

SEE ALSO
     dkpart(8), dkpsdfinit(8), format(8) [RM600 only], setinfo(8).











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