Largest production memcached install?

[Paul Querna]

Just Marc wrote:
> Hi Steve,
> 
> A bit off topic. I can't help but wondering:
> 
> Your memcache nodes are nice and beefy boxes (32G RAM, 4 cores of
> probably at leat 2GHz each -- that's generally a good amount of power
> for a database), maybe they don't have any spindles at all, though, but,
> if they did have a few, say up to 4, disks in each;
> 
> And you would split (federate) your database into 100 chunks (the
> remaining 100 would be hot spares of the first 100 and could even be
> used to serve reads), wouldn't that take care of all your database load
> needs and pretty much eliminate the need for memcache? Wouldn't 50 such
> boxes be enough in reality?
> 
> I do realize that 200 machines with no hard drives cost both less to buy
> and maintain. But what about 50? (just throwing random numbers). In the
> past you've also said that some of your memcache nodes do 30-60k
> reqs/sec, which would be very high in db speak, but I assume that that's
> the exception rather than the rule because 6 to 12 million memcache
> reqs/sec in aggregate sounds a bit out of this world.

It's not all that out of the world.  Consider how many distinct objects
need to be fetched to generate a single page.  If your caching model
caches individual objects, you could easy have 200 or more per page.

6 million / 200 = 30,000 Page views per second.

Maybe thats high, maybe its not, but it doesn't seem out of this world
to me.

For Bloglines, we commonly have pages that will do 200 to 1000 object
fetches from memcache.  Getting to 6 million+ aggregate memcache
requests per second is definitely feasible.

IMO, blah blah blah....

-Paul