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DISKSIM(8)                  System Manager's Manual                 DISKSIM(8)



NAME
       disksim - disk simulator

SYNOPSIS
       aux/disksim [ -r ] [ -f file ] [ -s srvname ] [ -m mtpt ] [ diskname ]

DESCRIPTION
       Disksim presents an in-memory disk in the manner of the sd(3) device on
       mtpt/diskname (default /dev/sdXX).  The disk is initialized  to  zeros;
       non-zeroed blocks written to the disk are kept in memory.

       When setting disk geometry with the geometry control message, the argu‐
       ments are sectors, sector  size,  cylinders,  heads,  and  sectors  per
       track.   The  last three may be zero for LBA disk simulations, but must
       be present.

       The -f option causes disksim to use file as the initial contents of the
       disk  rather than a zeroed image.  Changes made to the disk are written
       back to file unless the -r option is given.

       The -s option causes disksim to post its 9P service at /srv/service.

EXAMPLES
       Disksim can be used to test programs such as fdisk and prep(8) that ex‐
       pect sd(3) disks:

              aux/disksim
              echo geometry 40000 512 0 0 0 >/dev/sdXX/ctl # 20MB
              disk/mbr /dev/sdXX/data
              disk/fdisk -baw /dev/sdXX/data
              disk/prep /dev/sdXX/plan9

       Disksim  is  useful for creating very large but mostly zeroed files for
       testing other programs.  Test tar(1)'s handling of large files:

              for(i in sdXX sdYY sdZZ) aux/disksim $i
              echo geometry 40000000 512 0 0 0 >/dev/sdXX/ctl # 20GB
              echo geometry 10000000 512 0 0 0 >/dev/sdYY/ctl # 5GB
              echo geometry 20000000 512 0 0 0 >/dev/sdZZ/ctl # 10GB
              tar cf /dev/sdXX/data /dev/sdYY/data /dev/sdZZ/data
              tar tvf /dev/sdXX/data

SOURCE
       /sys/src/cmd/aux/disksim.c

SEE ALSO
       sd(3), prep(8)



                                                                    DISKSIM(8)