2010-11-01 10:56 PM
First, Ontap is the OS of the NetApp boxes. Clariion is a storage box from EMC (however I don't know any 420).
To see some difference, let's see the boxes. The Clariion is a block storage, supports FC and iSCSI connections while the NetApp boxes are unified, which means they support both file (NFS, CIFS, FTP...) and block (FCP, iSCSI) level access. Of course there are many differences, you'll get the most hit on google if you search 'netapp vs clariion'. Or you can try to ask specific questions, and we'll try to answer.