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 of the blocks to read from disk (default 100M).
-c
the number of times to read the entire disk.
-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.
AUTHOR
This program, it's manual page, and the Debian package were written by
Russell Coker <russell@coker.com.au>.
