Macbook pro, disk utility and external hard drive

I have a Macbook Pro running on Lion. My external hard drive is a Buffalo and used as data backup only, and is formatted to Macs.

I have used the ext. hard drive for two years with no issues. I am considering running "disk utility" (specifically "verify disk") to check its health. Is there a minimum or maximum amount of times you can run it on an external hard drive? I am aware of the different types of software you can buy, but running "disk utility" on an external hard drive is my only option right now.

Solution 1:

Internal or external makes no difference. it wont damage the disk in any way, it does not use up "write-cycles". the only useless option would be running verify permissions if you dont have an OSX installation on it.