NAME

       zcav - program to test raw hard drive throughput.

SYNOPSIS

       zcav  [-b  block-size[:chunk-size]]  [-c  count]  [-r  [first-block]:last-block]  [-w] [-s
       skip-rate] [-u uid-to-use:gid-to-use] [-g gid-to-use] [-l  log-file]  [-f]  file-name  [-l
       log-file [-f] file-name]...

DESCRIPTION

       This manual page documents briefly the zcav, program.

       Modern  hard  drives  have a constant rotational speed but have varying numbers of sectors
       per track (outside tracks are longer and have more sectors). This is referred to as  Zoned
       Constant  Angular  Velocity  (or  ZCAV). The outer tracks will have a higher data transfer
       rate due to having  more  sectors  per  track,  these  tracks  generally  have  the  lower
       track/sector numbers.

       This  program tests the ZCAV performance of a hard drive, by reading the entire data on it
       a specified number of times. The file name  given  as  the  first  parameter,  it  can  be
       specified  as  -,  for  standard input. This file will be opened as read-only and in usual
       operation it  will  be  /dev/hdX  or  /dev/ide/host0/busX/targetY/lun0/disc  depending  on
       whether  you  use  devfs or not (NB operating systems other than Linux will have different
       device names).

       The output should be able to be easily graphed with gnuplot which is what I  use  to  view
       the results.

OPTIONS

       -b     the  size  (in Meg) of the blocks to read/write (default 512M), optionally followed
              by a ':' and the chunk size for read/write operations (default 1M).  Note that  the
              chunk  size  must  be  less  than  or  equal  to  the  block  size and must also be
              significantly less than the size of the RAM in the machine.  Also note that for the
              write test there will be a fsync() after writing every chunk.

       -c     the number of times to read/write the entire disk.

       -r     the  range of data (in Meg) to read/write on each pass (default the entire device).
              Useful if you want to quickly test part of a large drive.  If a  single  number  is
              given  then  that is the last block to read, if two numbers then it's the start and
              end of a range.  Values are in megs, but they are rounded down to the block size.

       -s     skip rate.  The option -s 10 will cause it to read every 10th block  and  skip  the
              rest.  Accepts values from 2 to 20.

       -f     the file-name for the input data. This isn't needed on well configured systems that
              have a recent Glibc where you can specify the file name without the -f flag.

       -u     user-id to use.  When running as root specify the UID to run the tests  as,  it  is
              not  recommended  to  use root, so if you want to run as root use -u root.  Also if
              you want to specify the group to run as then use the  user:group  format.   If  you
              specify  a  user  by  name but no group then the primary group of that user will be
              chosen.  If you specify a user by number and  no  group  then  the  group  will  be
              nogroup.

       -g     group-id  to  use.  Same as using :group for the -u parameter, just a different way
              to specify it for compatibility with other programs.

       -w     write zero blocks to the disk instead of reading from the disk - will destroy data!

AUTHOR

       This program, it's manual page, and the Debian  package  were  written  by  Russell  Coker
       <russell@coker.com.au>.

AVAILABILITY

       The source is available from http://www.coker.com.au/bonnie++ .

       See http://etbe.coker.com.au/category/benchmark for further information.

                                                                                          zcav(8)