Squid and Multiple disks

Dear List, Does anyone know how to make Squid store it's cache on multiple disks. I have played with the cache_dir setting in the Squid.conf file, but can only get it to store the cache dirs on the first hard drive (sda) - whilst we want to use our second drive (sdb). Also, how do you format a disk in KDE3? It does not seem the same as in Windows. I want to format the second hard drive so that it is clean. Any help would be appreciated. Best wishes, Gareth Edmondson