please recommend a disk-exercising program?

[Wojciech Puchar]

> Hello list,
>
> Can anyone please recommend to me a program that will stress-test a
> disk? If it matters, two are connected by firewire, another via usb.
> Filesystem is ufs. I think I have a disk that might be about to fail,
> but it only sometimes errors when under stress. I need to see if it

if it's about to fail then simply read it

dd if=/dev/disk of=/dev/null bs=1m


if it will not - disk is most probably OK.