When not to use memcache

Question

Currently we are having a site which do a lot of api calls from our parent site for user details and other data. We are planning to cache all the details on our side. I am planning to use memcache for this. as this is a live site and so we are expecting heavier traffic in coming days(not that like FB but again my server is also not like them ;) ) so I need your opinion what issues we can face if we are going for memcache and cross opinions of yours why shouldn't we go for it. Any other alternative will also help.

Answer 1

https://github.com/steveyen/community-site/blob/master/db_doc/main/WhyNotMemcached.wiki

Memcached is terrific! But not for every situation...

• You have objects larger than 1MB.
  • Memcached is not for large media and streaming huge blobs.
  • Consider other solutions like: http://www.danga.com/mogilefs
• You have keys larger than 250 chars.
  • If so, perhaps you're doing something wrong?
  • And, see this mailing list conversation on key size for suggestions.
• Your hosting provider won't let you run memcached.
  • If you're on a low-end virtual private server (a slice of a machine), virtualization tech like vmware or xen might not be a great place to run memcached. Memcached really wants to take over and control a hunk of memory -- if that memory gets swapped out by the OS or hypervisor, performance goes away. Using virtualization, though, just to ease deployment across dedicated boxes is fine.
• You're running in an insecure environment.
  • Remember, anyone can just telnet to any memcached server. If you're on a shared system, watch out!
• You want persistence. Or, a database.
  • If you really just wish that memcached had a SQL interface, then you probably need to rethink your understanding of caching and memcached.