Lecture 6: Network Attached Storage

Terms you should know

Paul Krzyzanowski

March 4, 2021

Design

  • Transparency
  • Consistency
  • Security
  • Reliability
  • State and stateful vs. stateless designs
  • Service models: download/upload, remote access
  • Access semantics: sequential vs. session
  • Remote file service, directory service, client module
  • VFS interaction
  • File Caching

NFS

  • Original design goals
  • Use of UDP, state
  • I won’t ask about the mounting protocol
  • Directory & file access protocol; role of lookup RPC
  • Approach to caching, validation
  • Read-ahead
  • Consistency problems
  • Open with append & locking problems (original design)
  • Lock manager addition

AFS

  • Goal
  • Core design: whole-file serving & long-term caching
  • Cells, volumes
  • Namespace and Volume Location Database
  • Callback promise & callbacks
  • File access semantics
  • Referrals

DFS

  • Tokens (concept only; you don’t need to know all the types)
  • Token revocation

Coda

  • Goals
  • Volume Storage Group
  • Accessible Volume Storage Group
  • Resolution
  • Disconnected operation mode
  • Client Modification Log
  • Reintegration
  • Hoard database

SMB

  • Design goals
  • Message block
  • You don’t have to know the procedures - just the general idea of what they do
  • Oplocks - purpose, revocation, change
  • You don’t need to know the batch and filter oplocks
  • Read-cache, write-cache, handle-cache leases
  • DFS Namespaces

SMB Improvements

  • Pipelining (understand the concept)
  • Compounding (understand the concept)
  • Credit-based flow control

NFS4 Improvements

  • State, open
  • Compound RPC (understand the concept)
  • Locking
  • Cache control (understand the concept)
  • Callbacks

GFS

  • Parallel file systems

  • Master - role

  • Chunkserver - role

  • Replication

  • Operation log

  • Access model, client interaction Writing

    • chunk lease
    • primary replica
    • Two phases of writing
    • Pipelining
    • Commit
  • I will not ask about HDFS

    • You don’t need to know the differences between GFS and HDFS or the names of any of the Hadoop file system components

  • I will not ask about Dropbox

Last modified March 19, 2021.
recycled pixels