please recommend a disk-exercising program?

[Wojciech Puchar]

>
> I've seen several mentions of "dd" in this thread, and I'll say that I've
> seen several recommendations elsewhere to use a simple:
>
> 	dd if=/dev/<device> of=/dev/<device>

forgot bs=1m or at least 64kB, unless you like to wait days with default 
bs=512

>
> to "refresh" the drive.  That is, dd will read the block(s), then attempt to
> write them back, and if there are problems, the drive should re-map the sector


add conv=noerror,osync