Hi Friend,
Storage DRS is introduced in vSphere 5.0. You need to have enterprise plus license to get SDRS to work.
If you can satisfy above requirement, creating datastore cluster is very easy.
Even if you have only 1 host & 1 VC with 5.0 version, you can achieve this. You will have to migrate VMs one by one to 5.0 host from older version & attach all datastore to 5.0 host as that of older host. You can add all datastore into datastore cluster.
Plz refer below link for creating it from vsphere client.
From web client : (This link gives you more insight on it)
How to create a datastore cluster using the new web client. - frankdenneman.nl
To keep datastore in maintenance mode
Note:
-Collection of host is compute cluster. If you enable DRS on cluster, it helps to balance cpu & memory load on cluster & also initial placement.
-Collection of datastore is datastore cluster. : If you enable SDRS on cluster, it helps you to balance space & io load balance & initial placement.
-Both type of clusters allow to keep host or datastore into MM .
Let me know if you need any other info/help