Virtual vs Physical Disks

[PAz]

so basically the disk is thin = it only uses the space it needs and grows when required.

if for some reason a data file was to immediately grow and require an additional 10gb it would need to do the expansion on the back end whilst reading/writing = slower performance.

 

[Subliminal Aura]

Yep .... rather be fat than thin especially if you're running a RDMS

 

[Showboat]

You may also want to enable instant file initialization on your SQL server, probably won't make much difference. (Just give the sql service account the perform volume maintenance privilege in the local security policy).

 

[bods]

As others have said. Raw device mapping will give better performance than thick provisioned disk which in turn gives better performance than thin provisioned disk.

Perfmon will give you the indication that you need.