In addition to moving my servers to save costs, I ran into a two part issue that I lumped into: “I need to tune memory usage a bit”.
Part 1: Apache
Since I moved my Apache servers to lower memory instances, I was running into swap space usage that I could easily avoid, ie:
free -m
total used free shared buffers cached
Mem: 268 245 22 0 71 53
-/+ buffers/cache: 120 147
Swap: 511 29 482
Some of the reasoning behind this was that, by default, Apache expects a bit more memory to be available than what I provided to it in the move. The fix was to introduce a few settings to lower child processes and limit concurrent connections to something more reasonable to the type of traffic my site really gets – which is near nothing most days.
The settings I dropped into apache were:
httpd.conf:
#Low Memory Settings
StartServers 1
MinSpareServers 4
MaxSpareServers 2
ServerLimit 6
MaxClients 6
MaxRequestsPerChild 3000
I made the adjustments, cleared out the swap space with:
swapoff -a swapon -a
Then restarted apache:
/etc/init.d/apache2 stop /etc/init.d/apache2 start
And all was well in the world.
free -m
total used free shared buffers cached
Mem: 268 207 60 0 31 79
-/+ buffers/cache: 97 170
Swap: 511 0 511
Part 2-1: PHP
A bit simpler, my blog site was running into max memory allocation limits. I had left the default php.ini in place in the upgrade, so I needed to do a once over of configs and change memory_limit from 16M to something more reasonable for my site.
php.ini
memory_limit = 64M ; Maximum amount of memory a script may consume (16MB)
Part 2-2: APC
Having Apache settings set for lower memory usage also allowed me more room to increase my APC cache limit a bit higher to keep more pages faster. From 30 MB to 50 MB.
apc.ini
extension=apc.so apc.enabled=1 apc.shm_size=50
Other obvious solutions in consideration, switch to Rackspace to invert my memory/cpu requirement/cost ratios. Any other tips are welcome 