[Foundation-l] Q3 server budget adjustment ; J curve time for future budgets

Update - None of this is official yet:

After many hours checking and rechecking my numbers, I've found that my
previous preliminary estimate of $25K to $30K for a quarter 3 budget was a bit
off. The problem was with my estimate of the amount of money we previously
spent per 1000 hits over the last year. I figured *total* previous hits and
then applied that to projected *increases* in hits in the future. Thus my
estimate was too optimistic. 

After recalculating for past *increases* in traffic I've found that if our
traffic increases 90.53% over last quarter by the end of this quarter we will
have to buy $29K to $35K dollars worth of new servers to keep up with the
increase (if we don't have any traffic increase, then we won't have to spend a
dime unless a server has to be replaced). This figure includes a Moore's Law
adjustment which assumes we will be able to serve ~17% more hits per new server
dollar over last quarter (I'm still not 100% confident that that is a valid
assumption - any ideas?). The previous $25K to $30K estimate *did not* include
a Moore's Law adjustment.

Other possibilities: 
% growth        35.22%	    254.90%	20.00%     50.00%      100.00%
$/1000 hits	$11,274.81  $81,595.03	$6,402.22  $16,005.54  $32,011.09
Average		$13,609.25  $98,489.19	$7,727.79  $19,319.47	$38,638.95

NOTE: The 35.22% figure is the actual growth from Q1 to Q2 and the 254.90%
figure is the actual growth from Q4 2003 to Q1 2004. The average quarter to
quarter growth over the last couple years, however, is about 90%. But who knows
if this quarter will follow that or do something unpredictable like the last
two quarters. 

For the grant proposal I projected 90% quarterly compounded hit growth into
2006. The results are a bit shocking due to exponential growth. 

Year	annual budget
2004 	$110K - $132K
2005	$660K - $797K
2006	$4200K - $5078K

This assumes business as usual (meaning we continue to use the same kind of 
commodity-grade rack-mount servers and do not have any real time mirrors -
migrating to 'big-iron' servers and making use of a worldwide squid/mirror
system will mitigate for this). 

But there are still probably more errors in my estimates and I doubt we can
continue exponential growth for too long into the future (at least not at the
same absurd rate - 30% hit growth compounded quarterly would be much more
manageable but still exponential). 

I'll upload my spreadsheet to meta later so that others can check/improve my
analysis. 

Off to bed now though. 

Daniel Mayer,
Wikimedia CFO


	
		
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