In vSphere 6.5 VMware  doubled  the  current limits and continuously work on reaching new scale around this . Current limits (before 6.5) pose challenge as for example in some cases our customers have 8 paths to a LUN, in this configuration one can have max of 128 LUNs in a cluster. Also, many of the customers tend to have smaller size LUNs to segregate important data for easy backup and restore. This approach can also exhaust current LUN and Path limits.

Large LUN limits  enable  to have larger cluster sizes and hence reducing management over head.

SUMMARY:

• Current Limit is 256 LUNs and 1024 Paths ,
• This limits customer deployments requiring higher Path counts ,
• Customers requiring small sized LUNs for important files/data require larger LUN limits to work with ,
• Larger Path/LUN limits can enable larger cluster sizes, reducing the overhead of managing multiple clusters ,
• Support 512 LUNs and 2K paths in vSphere 6.5 .