[OpenAFS] cache settings -- how large is too large?

[Esther Filderman]

John,

I like to compare setting an AFS disk cache to some kind of black art.

I've found that there are many issues used in determining what
size cache to use -- and what flags to stuff onto AFSD, including:
 - speed of the CPU
 - amt of memory [hard and virtual]
 - use of machine [number crunching? mail reading & web surfing?]
 - number of users
 - amt of total disk space & how it's used

& probably some other things I can't think of 'cause I'm tired :(.

I have a couple of big number crunchers that have 200M caches and
are lightning fast, yet on the big user machine I found that anything
over 150 [if i recall correctly] slowed the machine down because it
was forcing the cache to keep track of zillions of little user files.

My opinion: You gotta experiment. Pain in the ass? you betcha.

e.
disclaimer: I'm currently using IBM AFS only. Argh.
----------------------------------------------------------------
     ecf@psc.edu     Esther Filderman    moose+@cmu.edu
           Senior System Mangler & AFS Dominatrix  
               Pittsburgh Supercomputing Center