Hello Storm IT, You can’t use your MD1420 to expand space on your MD3420, as MD1200 & MD1220 are the only supported enclosures.  An MD1420 can only be connected to a single server, so you will not be able to add it to your cluster as well.  If you have a single server that you need to have additional space, then you can add your MD1420 to that server.  Here is the link to the support matrix for both MD3420 & MD1420. MD3420= [URL] MD1420= [URL]
We are currently using a MD3420 that is storage for our cluster of 3 R730xd. Old manager got a MD1420 later that we havent used yet. Is it possible to use or attach the MD1420 to our current configuration? The 3 R730xd are currently using one HBA connection per a server. 
Is adding a MD1420 to current array possible?