1. A method to manage non-volatile storage (“NVS”) backup in a data storage system, comprising: supplying a data storage system comprising (n) clusters, wherein each cluster comprises a processor and a cache, and wherein each cache comprises a first NVS portion and a second NVS portion, wherein (n) is greater than or equal to 3; setting, for each value of (i), a primary NVS for an (i)th cluster in a first NVS portion of a cache disposed in an (i+1)th modulo (n) cluster, wherein (i) is greater than or equal to 0 and less than (n); setting, for each value of (i), a secondary NVS for an (i)th cluster in a second NVS portion of a cache disposed in an (i+2)th modulo (n) cluster.