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)