We've been discussing design of a data warehouse strategy within our group for meeting testing, reproducibility, and data syncing requirements. One of the suggested ideas is to adapt a NoSQL approach using an existing tool rather than try to re-implement a whole lot of the same on a file system. I don't know if a NoSQL approach is even the best approach to what we're trying to accomplish but perhaps if I describe what we need/want you all can help.
- Most of our files are large, 50+ Gig in size, held in a proprietary, third-party format. We need to be able to access each file by a name/date/source/time/artifact combination. Essentially a key-value pair style look-up.
- When we query for a file, we don't want to have to load all of it into memory. They're really too large and would swamp our server. We want to be able to somehow get a reference to the file and then use a proprietary, third-party API to ingest portions of it.
- We want to easily add, remove, and export files from storage.
- We'd like to set up automatic file replication between two servers (we can write a script for this.) That is, sync the contents of one server with another. We don't need a distributed system where it only appears as if we have one server. We'd like complete replication.
- We also have other smaller files that have a tree type relationship with the Big files. One file's content will point to the next and so on, and so on. It's not a "spoked wheel," it's a full blown tree.
We'd prefer a Python, C or C++ API to work with a system like this but most of us are experienced with a variety of languages. We don't mind as long as it works, gets the job done, and saves us time. What you think? Is there something out there like this?
Have you had a look at MongoDB's GridFS. http://www.mongodb.org/display/DOCS/GridFS+Specification
You can query files by the default metadata, plus your own additional metadata. Files are broken out into small chunks and you can specify which portions you want. Also, files are stored in a collection (similar to a RDBMS table) and you get Mongo's replication features to boot.
For me both Lustre and Ceph has some problems that databases like Cassandra dont have. I think the core question here is what disadvantage Cassandra and other databases like it would have as a FS backend.
Performance could obviously be one. What about space usage? Consistency?
来源：https://stackoverflow.com/questions/2776208/nosql-for-filesystem-storage-organization-and-replication