We have a Pressflow 6 app with Cache Router routing to multiple memcache bins. The bins have plenty of memory allocated, but other than that are running with default options.
In local testing, I've found that some basic cache-setting fails because of object size. Examples:
<20 set cache_views-views_data%3Aen 1 0 2721377
>20 SERVER_ERROR object too large for cache
<20 set cache_menu-links%3Aadmin_menu%3Atree-data%3A788912d6fd7adf98c8c86af7c57d00fe 1 0 1670355
>20 SERVER_ERROR object too large for cacheThese fail because the objects exceed the default 1 MB maximum object size. Overriding by passing memcached a larger value, e.g., -I 3m, leads to this warning:
WARNING: Setting item max size above 1MB is not recommended! Raising this limit increases the minimum memory requirements and will decrease your memory efficiency....But the SERVER_ERRORs go away, because all objects are storable.
I've noticed that (a) high-performance distros such as Pantheon run memcached with the default object size, and (b) people don't seem to encounter this error -- ever, if the silence on this and other forums is indicative.
Have you run into this before on sites with, e.g., very large views results? Have you had to tune memcached in this or other ways to resolve?