Server Config Calculator

	A	B	D	E	F	H	I	J	K
1	Settings		Service	config option		avg resp. time (ms)	avg reqs/sec	avg reqs/min	avg DB trans/sec

2	connection buffer (%)	50%	Gunicorn	workers	32	150	853	51,200	4,267
3	ulimit buffer	500	Gunicorn	worker_connections	1	200	640	38,400	3,200
4	# web servers	10	postgres	target active connections	60	250	512	30,720	2,560
5	# db servers	2	pgbouncer	max_client_conn (min)	96	300	427	25,600	2,133
6	avg DB transactions/page	5	pgbouncer	default_pool_size	6	400	320	19,200	1,600
7	redis conns per page view	1	postgres	actual active connections (max)	60	800	160	9,600	800
8	requests/second coeffecient	0.4	postgres	max_connections (min)	100	1,600	80	4,800	400
9			redis	maxclients (min)	480	3,200	40	2,400	200
10			redis	ulimit (min)	1000	6,400	20	1,200	100
11			rabbitmq	ulimit (min)	1000
12			memcache	connections (min)	480
13			memcache	ulimit (min)	1000
14	Notes:
15	Bolded items can be modified
16	Connection buffer is % of additional pgbouncer & postgres connections to reserve, on top of what's needed
17	Postgres max_connections should be determined based on machine resources; see http://wiki.postgresql.org/wiki/Number_Of_Database_Connections, http://thebuild.com/presentations/not-my-job-djangocon-us.pdf
18	The requests/second coefficient represents "efficiency" of the web servers and is adjusted based on the avg reqs/sec seen for a response time of around 200ms, in the real world
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