how to create redundancy for existing stack switch?

[rrairineo1]

Hi. how can i introduce redundancy to avoid failover of services running in two different stack switches? Before, one of the stack switches failed and some of the services in our network were affected. how do i introduce redundancy to this current setup to avoid point of failure. please see attached file for diagram. 

[Joseph W. Doherty]

With some 6500s or some 4500s, you have the option of VSS.  Two units operate like one device.  An advantage of VSS, you're not limited by the length of the special stack cables.