[Dovecot] rule of thumb for indexing overhead

[WJCarpenter]

wjc> I realize it's hard to be precise about this, but does anyone
wjc> have a feel or rule of thumb for a couple of aspects of indexing
wjc> overhead?

ss> You can always put the indexes in non-quota space like var. That
ss> way the indexes don't get counted against the users files, and
ss> won't get corrupted if a user goes over quota.

Thanks, but I think you misunderstood my question.  I'm trying to
figure out how much disk space I'll actually need for holding the
index files.  In other words, I'm looking for a planning factor to
figure out how much disk to buy when I got to Fry's :-).

(I'll be using the Dovecot quota stuff, so index files are already not
in the count.)