Largest production memcached install?

[Cal Heldenbrand]

Steve,

Just curious what are the OS load averages on your database servers?  Have
you expanded facebook to the point where losing most of the memcache servers
would cause your entire application to grind to a halt?

During my initial thoughts on integrating memcache into our product, I could
see it eventually becoming a crutch and we wouldn't have enough database
hardware to support the application anymore.  I wonder if that's a good
thing or a bad thing?

Thanks!

--Cal

On 5/3/07, Steve Grimm <sgrimm at facebook.com> wrote:
>
>  We rebuild from the database. We have enough memcached servers that
> losing one has a relatively small effect on our cache hit rate. Not to say
> there's no effect -- our DB load spikes up for a little while when we lose a
> memcached server -- but we build out our infrastructure such that even at
> peak load, repopulating an empty memcached instance or two doesn't slow
> things down noticeably for the users.
>
> -Steve
>
>
> On 5/3/07 12:23 PM, "Murty Chittivenkata" <murty at aol.net> wrote:
>
> Steve,
>
> are you replicating the hash data to hotspares or rebuilding in the event
> of failure from backend database?
>
>
> Thanks
> Murty
>
>
>
>
> We have a home-built management and monitoring system that keeps  track of
> all our servers, both memcached and other custom backend stuff. Some  of our
> other backend services are written memcached-style with fully
>  interchangeable instances; for such services, the monitoring system knows
> how  to take a hot spare and swap it into place when a live server has a
> failure.  When one of our memcached servers dies, a replacement is always up
> and running  in under a minute.
>
>
>
>
>
>


-- 
Cal Heldenbrand
   FBS Data Systems
   E-mail:  cal at fbsdata.com
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