PRACE NPT

.TH zcav 8

.SH "NAME"

zcav \- program to test raw hard drive throughput.

.SH "SYNOPSIS"

.B zcav

.I [\-b block\-size[:chunk\-size]] [\-c count] [\-n num_blocks] [\-w]

.I [\-u uid\-to\-use:gid\-to\-use] [\-g gid\-to\-use]

.I [\-f] file\-name

.SH "DESCRIPTION"

This manual page documents briefly the

.BR zcav ,

program.

.P

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.

.P

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

.BR \- ,

for standard input. This file will be opened as read\-only and in usual

operation it will be

.BR /dev/hdX

or

.BR /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).

.P

The output should be able to be easily graphed with

.BR gnuplot

which is what I use to view the results.

.SH "OPTIONS"

.TP

.B \-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

chunk.

.TP

.B \-c

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

.TP

.B \-n

the amount of data (in Meg) to read/write on each pass (default the entire device).

.TP

.B \-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.

.TP

.B \-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

.B \-u root.

Also if you want to specify the group to run as then use the

.B 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

.B nogroup.

.TP

.B \-g

group\-id to use.  Same as using

.B :group

for the

.B \-u

parameter, just a different way to specify it for compatibility with other

programs.

.TP

.B \-w

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

.SH "AUTHOR"

This program, it's manual page, and the Debian package were written by

Russell Coker <russell@coker.com.au>.

.SH "AVAILABILITY"

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

.P

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