Hi,
It's been some time since we've expanded our server configuration at
wikiHow. We currently have 5 servers (1 Squid, 3 Apache and 1 DB) and
I have some questions about planning for future growth. We do make use
of memcached and eaccelerator, Squid occasionally reaches 300 requests
per second, and we get about 5.5 million unique visitors a month
growing at about 10% per month. All servers are dual Opteron 64bit,
4GB of RAM, with 3x73GB SCSI drives.
Does anyone know how it's possible to estimate how much available
cushion there is for a given Apache server? Is there an upper limit on
the number of requests per second or server load? Basically, at what
point can you be sure that you need to add more Apache servers?
The ratio of Squid to Apache server should be about 1:10, correct?
Once you add a 2nd Squid, what the best way to load balance between
the 2?DNS round robin or use a hardware load balancer?
When should a 2nd database server should be added? Are there any other
optimizations we could be benefiting from?
If anyone has any input, it would be much appreciated.
Travis