nosql vs rdbms hardware specs

Generally its believed that RDBMS scales better vertically while nosql are designed specifically to scale horizontally.

What kind of databases would be better fit for this kind of hardware http://www.dell.com/us/enterprise/p/dell-compellent-storage-center/pd.aspx

which can scale up to many hundred TBs.

As nosql databa开发者_StackOverflow社区ses are typically designed to be run on commodity servers then what should be the specs of that commodity server considering a very high load on database.

And what would be limit of RDBMS hardware node.. considering that enough RAM is available to have indexes (not dataset) in memory all the time.

While NOSQL has not hard requirement of indexes in RAM (but of course its recommended).

It would be also very interesting to know what are best fit for SAN devices? like http://www-03.ibm.com/systems/storage/disk/ds3500/index.html which can hold many hundred TBs at same place.

The decision whether to use NoSQL databases or to use Relational databases should come from your use case/application rather than your hardware. Analyze your use case, determine whether to use RDBMS or NoSQL Database (If NoSQL, then which NoSQL database to use is another crucial question, the answer to which will again depend on your use case). Then buy hardware which would be needed to run what you have decided.

The machine you link to can run RDBMS and NoSQL both, depepnding on what you need to do with your data. In case of MongoDB and HBase, commodity servers generally means 4-core machines with 16-24GB RAM. HBase starts showing good results only after you have at least 6-7 machines on your cluster. In case of other NoSQL DBs it might be different.