Read/WRITE/Verify disk diagnostic tool for Mac OS X?

Solution 1:

You might want to have a look at badblocks(8), a command-line tool from GNU/Linux. There is a port for Darwin, which you can get from MacPorts:

sudo port -v install e2fsprogs

Having a look at the manual, you can read the -n and -w options' paragraphs:

-n Use non-destructive read-write mode. By default only a non-destructive read-only test is done. This option must not be combined with the -w option, as they are mutually exclusive.

-w Use write-mode test. With this option, badblocks scans for bad blocks by writing some patterns (0xaa, 0x55, 0xff, 0x00) on every block of the device, reading every block and comparing the contents. This option may not be combined with the -n option, as they are mutually exclusive.

Hopefully this is what you are looking for.

Solution 2:

The digilloyd disc tester does read/write/verify and is fabulous to boot.

More HERE