Its questions like these that make managers hate IT. (Unless its the manager
asking this question which indicates he has no idea what IT does.) Its
really not the quantity that matters. Its the level of service. Your peers
and you define a set of acceptable SLA's (Service Level Agreements.)
Basically, how much downtime/response time is acceptable for any foreseeable
problem. If the boss says the company can be without email for no more than
2 hours, than you have to plan for that contingency, taking into account
your normal workload.
In your example, 25 servers in a slow paced, stable-hardware company can
easily be managed by 1 person. In a high transaction, volatile environment,
it may take 3 or more. Your helpdesk for clients will be managed the same
way, but will be more subject to scrutiny. Your servers can have a hiccup &
the employees may not know, but when the helpdesk takes 3 days to fix a
printer, everyone knows. The big assumption become whether your "senior"
people really know what they are doing. "Senior" IT people in my
organization are not the ones with the earlier start date, but the ones that
have the best combination of customer satisfaction and skill set.
In my humble opinion, I would do your best to steer clear of hard numbers as
far as quantity expectations. While they can help you now get that extra IT
guy, they can also hurt you down the road when you roll out the questionable
ERP package (or whatever management cooks up next) and are hurting for man
hours to correct it. You are now locked into your manpower budget.
Keep the SLA at the forefront of your IT planning and you can add & remove
people/hardware as necessary based upon the requirements you and management
came up with during SLA creation.
[steps off soap box. . .]
