"The challenge for the shared-disk architecture is the need to coordinate cached data across nodes. Without an in-memory cache, performance for all operations will degrade to disk speed. But to maintain a consistent view of data across all nodes, each node needs to maintain a consistent cache. Maintaining this cache coherency puts a strain on the network between the nodes and is difficult to successfully implement."
via Check out this quote from Next Generation Databases: NoSQL, NewSQL, and Big Data - https://learning.oreilly.com/library/view/next-generation-databases/9781484213292/9781484213308_Ch08.xhtml
- Shared-everything
- Shared-disk
- Shared-nothing
"To date, the only surviving commercially successful shared-disk RDBMS is Oracle’s Real Application Clusters (RAC) cluster database. RAC is the basis for Oracle’s Exadata database machine and cloud database offerings."
via Check out this quote from Next Generation Databases: NoSQL, NewSQL, and Big Data - https://learning.oreilly.com/library/view/next-generation-databases/9781484213292/9781484213308_Ch08.xhtml
OracleのRACはShared-everythingと言われることが多い気がするが、確かにShared-diskの方がより適切な表現に思われる。今日日Shared-diskはOracleのRACだけらしい。技術は多数派が正解という訳でもないから、マーケットに受け入れられている以上はShared-diskも正解なのだろう。
