• NFS:
  • Primary file system for clusters, and is pretty much” plug and play” on most *nix systems.
  • It was the first popular file system that allowed distributed systems to share data.
• NFSv3:
  • The most popular version of NFS. It was released around 1995 and
  • added several features including support for 64-bit file sizes and offsets (so it can handle files larger than 4GB), asynchronous write support, and TCP as a transport layer.
• NFSv4:
  • Around 2003, NFSv4 was released with some improvements. In particular,
  • it added some speed improvements, strong security (with compatibility for multiple security protocols), and NFS became a stateful protocol.
• NFS 的效能面：
  • The good news for NFS and NAS is that many codes don’t require lots of I/O for good performance. These codes will run very well using NFS as the storage protocol even for large runs (100+ nodes or several hundred cores). NFS provides adequate performance until the input and output files for these codes become extremely large, or if the code is run across a very large number of processors (in the thousands).
  • NFS still lacks the performance and scalability required by many large clusters, but that is about to change.
• pNFS (NFSv4.1):
  • adding PFS capability to the NFS protocol. The goal is to improve performance and scalability while making the changes within a standard (recall that NFS is the only true shared file system standard).
  • this standard is designed to be used with file based, block based, and object based storage devices with an eye towards freeing customers from vendor lock-in.
  • pNFS Architecture,
    • pNFS Sever 連接 Client 和 Storage ，當 Client 要存取檔案時先至 pNFS Server 查詢 Metadata 找到檔案的位置，再連接到存放檔案的 Sotrage