Running Oracle 11g 2-Node RAC on Only Single Node

Customer wants to be convinced that if one node goes down on our two node Oracle RAC 11g database, we will continue processing; albeit perhaps with some latency.  And of course; how much latency. Recently we had a minor glitch at our customer's site, where a Solaris Cluster resource faulted.  This particular cluster resource is associated with our ASM disk groups, "asm_dg_rs".  After much investigation, a standard ASM query, that happens as part of this resource check was taking longer than the expected value of 120 seconds.  Long story short, in summary the query was taking longer because the actual hardware was extremely bogged down.  The server was doing a "zfs scrub", which I now understand scrubbing is similar to the file system check, “fsck”, as it validates blocks on the disks. The
zfs scrub” was scheduled once a week, so we canceled the weekly scheduled job.  The hardware team has since decided the our (2) R810 Dell Servers are memory starved, and the memory will be severely upgraded.  Apparently there was an extreme amount of paging occurring.

So, because of this minor resource fault, that I thought was well explained and solved – customer is extraordinarily concerned about a failure during a critical event.  How can I convince my customer, than our high availability Oracle RAC 11g 2-node database will be able to keep on ticking and mostly like not miss a beat?  Part of the RAC technology of high availability is fault tolerance, where you should be able to continue with a server down in the cluster – correct?