Don’t place /var/cache/ on a network file system at all. Instead, caches should be only local on the machine and best placed on an SSD storage. Usually, it also doesn’t matter if items are cached several times at several machines.

Is there any way out of using a network storage if you need to be able to scale your pods? NFS and especially GlusterFS are _heavily_ noticable in the backend. Talking about sizable time spent on hundreds file operations like file_exists or file_get_contents..