In most of the cases, LRU should be good enough. If the 'important' items
are used very often, they will be naturally kept in cache. Locking some
rarely-used items in cache, I cannot see the justification for the cost of
discarding other often-used items and constantly re-creating them as they
are referenced frequently.
Yes and no. Looking at some real world cases (our) we have experienced that
objects without specified ttl (which kinda qualify as permanent items) get
evicted more/quicker rather than those with expiration set (as they prolly
fall in to the same slabs). At some time we get to the point where a newly
created item is pushed out few moments after it is added. Well you can say
it shows that memcache needs more ram, but we are allready running on ten 30
gig instances with zilion of items :)
Running seperate servers with different settings is an option but imho
throws out the window whole idea about transparent horizontal
scaling/growing of memcached servers..
Anyway my point here was just to give some hints to the initial questions..
As there have been answers to different proposals like full cache dumps,
replications, bdb backends and so on (I have always liked the responses to
be superfast rather than feature-rich bloat) but noone really has answered
to Pauls mail it was an opurtunity to throw it in again :)
rr
