[CentOS] Server to server communication

Wed Mar 19 05:21:11 UTC 2008
Les Mikesell <lesmikesell at gmail.com>

D Steward wrote:
>> How often does the data change and how critical is it to have real-time 
>> results.  Web sites often have thousands of people getting copies of the 
>> same thing, or at least computed from the same values even if they are 
>> the same only for a short period of time. 
> The servers will exchange sensitive data hopefully with a latency of <
> 50ms.
> Ping time between them is 20ms.

That's not the relevant question.  How often does the data change 
relative to the number of times you re-use it?

>> One approach is to put 
>> memcached between your web application and the database for extremely 
>> fast repeated access to the same data. It is just a cache layer, though, 
>> you still need a persistent database underneath. 
>> http://www.danga.com/memcached/
>>
> Ahh, thanks. I forgot about memcached. I am presently using some
> in-memory MySQL tables, but I'll have to benchmark this against
> memcached.
> But the 2nd server was procured to relieve the CPU load on the main one.
> Even with a 16-way Opteron, this situation would have had to be faced
> eventually.

The big advantage of memcached is that you can distribute it over as 
many servers as you need to keep everything in RAM - and have it shared 
by any number of clients.

-- 
   Les Mikesell
    lesmikesell at gmail.com