I have 2 no SAN and 3 ESXI hosts. Now I want to create the storage fault tolerance. Please tell me the best option.
Hello,
Your question is not clear, you mean VM in Fault Tolerance. ?
No, datastore cluster is not your choice for such a functionality.
You would, probably, like to look at native storage array sync functionality (they usually have those) or at vSphere Replication.
Or maybe vSAN feature.
Or, depending on your goals, you might create two virtual disks on different SANs and combine them into RAID1 ("mirror") at guest OS level (I'd not recommend this way though).