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network filesystem briefs

network filesystem briefs






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network filesystem briefs network filesystem briefs Presentation Transcript

  • Network File Systems Briefs [email_address] 3/20/2010
  • Index
    • DEC-DAP
    • SUN-NFS
    • AT&T-RFS
    • CMU-AFS
    • CMU-Coda
    • Microsoft-CIFS
    • NetApp-Filer
    • EMC-MPFS
  • Topic-File Storage
    • Block storage vs. file storage.
    • Block storage: EMC and Hitachi.
      • Block I/O access
      • Devices may be directly attached (SCSI or Fibre Channel) or distant accessed (iSCSI or AoE)
    • File storage: NetApp and EMC Celerra.
      • File I/O access
      • Files and directories are present over the network.
  • NEC-DAP (Data Access Protocol)
    • Created in 1976
    • First wildly used network file system
    • A FAL (File Access Listener) is created on each data node to serve network-based access requests.
    • Use local file system to manage local device
  • RPC war-Sun ONC vs. Apollo NCS
    • 1980s.
    • ONC (Open Network Computing Remote Procedure Call, now SunRPC).
      • Always in big-endian order.
    • NCS (Network Computing System)
      • Avoid byte-swap if two peers share a common endianness.
  • SUN-NFS (Network File System)
    • Built on top of SUN RPC.
    • V1: in-house development
    • V2: RFC1904. 1989. First release. Stateless. UDP based. Without lock management. Big bull authors (including Bill Joy).
    • V3: RFC1838. 1995. 64-bit support. Asynchronous writes. TCP support. READDIRPLUS operation to get file handle and attributes while scanning dir.
    • V4: RFC3010 and 3530. Learn from AFS and CIFS. IETF. Performance. Security. Session. Includes a stateful protocol.
    • NFS semantic: flush on close
      • check return value of close(2) when working with NFS !
  • SUN-NFSv4.1
    • pNFS – MPFS
    • Directory delegation and notifications
      • Clients can have read-only delegated dir. So local cache is enough for any reads.
      • Server sends change notifications to clients that have delegated dir.
    • Multi-serve namespace
      • Server replicas to serve requests from clients
  • AT&T-RFS (Remote File System)
    • 1980s. SVR3 (Unix System V release 3). Bell lab production.
    • Stateful. Lock management.
    • Complete UNIX/POSIX semantics.
    • Mount devices over network.
    • Digital Equipment, HP and IBM adopted NFS over RFS.
  • CMU-AFS (Andrew File System)
    • 1988. Named after Andrew Carnegie and Andrew Mellon. Part of Andrew project.
    • Kerberos (C/S auth protocol from MIT) for authentication.
    • ACL on dir.
    • Client cache on local file system.
    • Cache consistency—Callback. Server saves all cache information and sends update notify if file changed.
    • Doesn’t support large shared file updating.
      • Single file per message in Andrew Message System, vs. single file per mailbox.
    • Volume. Volume quota. Read-only volume replicas.
    • Shared and local namespace.
    • Predecessor of Transarc, OpenAFS, Arla and Coda.
  • CMU-Coda
    • 1987. From AFS-2
    • Client side persistent cache and logged write updates.
      • Local/global conflicts
    • Server replication, allow all servers to receive write updates.
      • Server/server conflicts
    • Extensive repair, both manual and automated.
    • Continued operation during partial network failures.
    • Network bandwidth adaptation.
    • Open Software Foundation(1988). HP, IBM against SUN and AT&T.
    • Developed by Transarc, based on AFS.
    • DCE/LFS (Local Journaling file System, aka Episode) as local cache layer. Improve write performance even over slow network connections.
    • Filesets management.
    • Transarc bought by IBM. OpenAFS announced by IBM in 2000. DCE/DFS killed by IBM in 2005.
  • Microsoft-CIFS (Common Internet File System)
    • AKA SMB (Server Message Block) protocol, originally designed at IBM.
    • Modified and Merged by Microsoft with LAN Manager product in 1990.
    • Renamed to CIFS in 1996.
    • Samba – reverse engineering open source implementation.
    • Opportunistic locking.
      • Batch Locks: client delays sending close request. If a subsequent open request is given, the two cancels each other.
      • Exclusive Locks: If obtained, client may cache all changes before committing. If others open the same file, server sends revocation notify and client flushes all changes.
      • Level 2 OpLocks: After revoking a exclusive lock, server may send Level 2 OpLocks to allow client to cache read but exclude write.
  • Microsoft-CIFS cont.
    • SMB2 in 2006 (Windows Vista). Specification published.
    • Samba 4 adds support for SMB2.
    • Reduce control messages from over a hundred to nineteen.
    • Request pipelining: allow sending requests before response to previous req returns.
    • Compound multiple action in a single request.
    • Larger buffer size and symbolic links.
    • Durable file handle, allows a connection to survive brief network-outage without having to negotiate a new session.
  • NetApp-Filer
    • AKA NetApp Fabric-Attached Storage (FAS).
    • Originally NFS/CIFS based NAS solutions.
    • FTP, TFTP, HTTP, FC (Fiber Channel) and iSCSI are added later.
    • WAFL (Write Anywhere File Layout).
      • Read-only and read-write (FlexClone) snapshot.
      • Two directory models (UNIX and Windows) and two file security models (ACL and bitmask)
      • Consistency points.
      • Automatic fragmentation, saving metadata anywhere on the disk, usually beside its data blocks.
  • EMC—MPFS (Multi-Path File System)
  • More Over
    • Clustered file system.
      • Shared disk.
      • Translation from file-level ops to block-level must be done on client nodes.
      • Examples?
    • Distributed file system.
      • Similar to clustered file systems.
      • Replication and fault tolerance.
      • NFS, CIFS, AFS, Google GFS, etc.
    • Clustered NAS
      • Stripe data/metadata across the cluster of nodes.
  • Thank YOU~~ Most of the contents are taken from Wikipedia. No copyright reserved except that of others’.