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Does ONTAP support CIFS/SMB NDO?

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Applies to

ONTAP 9

Answer

  • NDO is Nondisruptive Operation, which is a fundamental capability of clustered Data ONTAP
  • Due to the fact CIFS/Server Message Block (SMB) being a STATEFUL protocol, it would still prevent continuous data availability in some nondisruptive operations
  • With the introduction of newer versions of SMB & clustered Data ONTAP, some improvements have been implemented
    • SMB1.0 could not survive a network outage due to the inherent limitations of the protocol without durable or persistent file handles
    • SMB2.0 introduces durable handle, an open file handle which is preserved during a short network outage so that the client may reconnect when the network comes up
    • In clustered Data ONTAP 8.2, NDO for SMB 3.0 is introduced for Microsoft HyperV environments with Continuously Available (CA) File Shares to better support NDO, which could provide better continuous data availability

Below is a chart of CIFS/SMB NDO Overview:

                       NDO                        SMB 1.0               SMB 2.x and SMB 3.0         SMB 3.0(Hyper-V only)
               LIF migrate                      Disruptive                   Nondisruptive              Nondisruptive
              Volume move                     Nondisruptive                   Nondisruptive              Nondisruptive
             Aggregate relocate                     Disruptive                   Disruptive              Nondisruptive
            Storage failover                     Disruptive                   Disruptive              Nondisruptive
  • Note: Applications connected to SMB 2.x file shares might still incur a disruption when the application allows multiuser access to the same file or for applications that do not pick up an open file handle within 15 minutes from when the LIF migrate was executed
  • In other words, even with durable handle enabled in SMB 2.0 or later, it could still prevent continuous data availability as durable handle might not be successfully granted
    • For detailed information, see TR-4100.

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