It’s a secret, which was lately published in a research paper by Google itself. The question is; how Google manages to store such a gigantic amount of data generated across various applications on it servers and that too with 99.99% availability?
To understand the answer, you need a little bit knowledge of RDBMS (a Google search would give you some answers) & NoSQL. Though explaining the concepts behind these complex database systems is quite lengthy, just understand that, these are database systems used to store data, though they differ significantly in the way they store data. There’re some other innovations like Google File System, which might interest curious minds to read through.
The storage system is called as ‘Megastore’ and as name suggests, it helps in storing real time data across disparate servers located across globe. It’s perfect blend of scalability of NoSQL & convenience of RDBMS.
Megastore is designed to replicate file write operations synchronously across a wide-area network with reasonable latency and support for graceful failover across data centers. It aims to strike a middle ground between the scalability of NoSQL databases and the convenience of a traditional RDBMS.
Google also discussed the fact behind rejection of MySQL, RDBMS & Oracle before innovating something like Megastore in the paper. Oracle, apparently the most capable among all, was rejected owing to cost propositions.