Forum: NGINX Proxy Cache: how much shared memory is "enough"?

Hi,

I'm planning to deploy some big websites which will make heavy usage of
proxy cacheing (e.g. 1.5 million actively accessed objects in cache). 
The
ratio of plain HTML vs images should be about 50/50 if that does have 
any
impact on the scenario itself. Now the question which came up is how 
much
Shared Memory for such a cache is enough. The docs don't really say very
much about that. So may be one of you can give me a hint on how much 
memory
is suitable for such a deployment.

Thanks in advance.

Regards,
Christian

Hello!

On Mon, Dec 10, 2012 at 10:37:30PM +0100, Christian Bönning wrote:

> I'm planning to deploy some big websites which will make heavy usage of
> proxy cacheing (e.g. 1.5 million actively accessed objects in cache). The
> ratio of plain HTML vs images should be about 50/50 if that does have any
> impact on the scenario itself. Now the question which came up is how much
> Shared Memory for such a cache is enough. The docs don't really say very
> much about that. So may be one of you can give me a hint on how much memory
> is suitable for such a deployment.

Each object in cache uses 128 bytes of memory in keys shared
memory zone on 64-bit platforms, as outlined on wiki here:

http://wiki.nginx.org/HttpProxyModule#proxy_cache_path

So for 1.5 mln objects you'll need about 200M of memory.

--
Maxim Dounin
http://nginx.com/support.html

Seems that I should have read the docs better ;)

Thank you, Maxim.

Regards,
Christian



2012/12/11 Maxim Dounin <mdounin@mdounin.ru>