I have a server runing BM 3.7 with two harddisks (9GB).
I know it is adviced to have two or more cache volumes.
But I want to duplex my other volumes.

Is it wise to add an extra harddisk (20GB) and use that disk for the
cache volumes?
What is the benefit of more cache volumes?
Is the benefit still there if all volumes are on one physical disk?

Kind regards,