Should my memcache stats worry me? Oldest item 10-20 minutes, 10mb size, 65% hit rate. Seems low..?

[Per]

Hi all,

I never really paid attention to the memcache stats, but after my app felt slow the past couple of days I started checking the stats more regularly. It's been between 5mb and 15mb the last three days, there are between 200 and 1000 items in it, and the oldest item was between 5 minutes and 20 minutes old. The hit rate is between 60% and 70%.

We typically have between 1 and 3 instances running, with maybe 0.5 requests per second on average. Based on gut feeling I'd say it would be beneficial if the memcache wasn't evicted that quickly, we should see higher hit rates if items were allowed to stick around for an hour or so. 

I'm curious, what are everyone else's experiences? Or is there maybe even some suggested approach to increase this? I searched, but couldn't find anything relevant, only complaints about memcache failures :)

Cheers,
Per
(small-improvements-hrd)

[brianl]

I recently made a change to do more in memcache.   Before I was seeing a hit ratio in the low 90's.  Now I'm seeing it in the low 70's.  I enabled billing to try F2 instances thinking that having more memory (256 Mb) would improve things.  The hit ratio is in the low 80's.   I'm not sure what to try next, perhaps this is the best it will do which seems unacceptable. 

-brian