Re: [SAGE] number of eggs in a basket

[Ruth Milner <rmilner@nmt.edu>]

John Sechrest wrote:

>  We know from Pattersons work that 90% of outages are a result
>  of mis-steps by system administrators. 
>  So adding 10 times the hardward does not mean that the 
>  number of outages will go up by a factor of 10.

What I said was that it was "10x more likely that some sort of
hardware or *system software* problem will take out a service".
I didn't put a number on the overall *total* number of failures,
only that it would increase (which is absolutely the case). The
cause doesn't really matter, though: if you have 10x the number
of machines for sysadmin missteps to be made on, then the overall
total failure incidents are likewise going to increase - though
not necessarily linearly.

 > if you simplify the configuration issues by eliminating
 > interdependencies

Or, to phrase it as I did:

   Interdependencies can actually be reduced by separating services.

We are not in disagreement AFAICT.

 >  So this is more complex than presented.

Well, I did say a little more than just that one quoted paragraph.
:-) My point in that bit was where the idea might come from that
the number of failures would increase by decentralizing, which at
least one respondent had questioned.

This does not make decentralization bad; as everyone has been
saying (including me), it's a complex issue. The point is that
decentralization also has costs that shouldn't be glossed over,
especially in a small shop.

Ruth Milner