system admin staffing requir.(35unix ser

The environment includes 22 mission critical systems ranging from sun e3000’s to sun e6500’s and ibm sp with 3 nodes(2 miss crit) and 2 risc6000 machines(1 miss crit). Responsibilities include everything from hardware setups, os/software/patch installs & configs, disaster recovery ,volume manager, disksuite, netbackup, networker. Applications
where some support is required include webphere,SAP,oracle,progress,etc. This is a 7×24 shop with 7×24 oncall pager requirements. The question here is,what is the minimum number of system administrator/s, that would be required to maintain this environment and what skill level is required?