Multiple nginx instances share same proxy cache storage

[Maxim Dounin]

Hello!

On Mon, Aug 04, 2014 at 07:42:20PM -0400, badtzhou wrote:

> I am thinking about setting up multiple nginx instances share single proxy
> cache storage using NAS, NFS or some kind of distributed file system. Cache
> key will be the same for all nginx instances.
> Will this theory work? What kind of problem will it cause(locking, cached
> corruption or missing metadata in the memory)?

As soon as a cache is loaded, nginx relies on it's memory data to 
manage cache (keep it under the specified size, remove inactive 
items and so on).  As a result it won't be happy if you'll try to run 
multiple nginx instances working with the same cache directory.  
It can tolerate multiple instances working with the same cache for 
a short period of time (e.g., during binary upgrade).  But running 
nginx this way intentionally is a bad idea.

Besides, using NFS (as well as other NASes) for nginx cache is a 
bad idea due to blocking file operations.

-- 
Maxim Dounin
http://nginx.org/