The first question is 'why add this capability? isn't the whole point of a virtual directory provide real-time access to backend data?' In my conversations, I basically received one answer: performance. Virtualizing and transforming the data can slow things down a bit.
Clayton Donley makes a case against persistent cache in an older post. To summarize:
- Persistent cache will mean data isn't real-time, which means the 'freshness' of data will be compromised.
- There are security concerns with adding another place to keep the data.
- There is pain associated with managing yet another directory.
(i.e., if you want a metadirectory, then get a metadirectory!)
So, I've come up with a few questions, and was wondering if anyone has any thoughts about it...
- Since performance is the main point here, does any one have numbers on the performance hit caused by virtual directories?
- Is performance the only real justification for persistent cache?