zcav - program to test raw hard drive throughput.
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]...
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
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.
-b the size (in Meg) of the blocks to read/write (default 100M),
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
-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.
-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
-w write zero blocks to the disk instead of reading from the disk -
will destroy data!
This program, it’s manual page, and the Debian package were written by
Russell Coker <firstname.lastname@example.org>.
The source is available from http://www.coker.com.au/bonnie++ .
See http://etbe.coker.com.au/category/benchmark for further