NFS and CIFS in Clustered DATA ONTAP
NFS and CIFS in Clustered DATA ONTAP
Data ONTAP supports several versions of the Server Message Block (SMB) protocol on your Vserver’s CIFS server. Data ONTAP support for SMB for Vservers with FlexVol volumes and Vservers with Infinite Volumes differ. You need to be aware of which versions are supported for each type of Vserver. NFS and CIFS in Clustered DATA ONTAP
Data ONTAP supports the following SMB versions for Vservers with FlexVol volumes and Vservers with Infinite Volumes: NFS and CIFS in Clustered DATA ONTAP
|SMB version||Supported on Vservers with FlexVol volumes?||Supported on Vservers with Infinite Volumes?|
Supported SMB 1.0 Functionalities
The CIFS (SMB 1.0) protocol was introduced by Microsoft for Windows clients. Data ONTAP supports the SMB 1.0 protocol on all versions of clustered Data ONTAP and on Vservers with FlexVol volumes and Vservers with Infinite Volumes. NFS and CIFS in Clustered DATA ONTAP
Over the years, Microsoft has extended the original SMB 1.0 protocol with enhancements to security, file, and disk-management features. Legacy Windows clients (pre-Windows XP) or non-Windows clients that support only SMB 1.0 can access data on the Vserver using CIFS over SMB 1.0.
Supported SMB 2.0 Functionalities
Data ONTAP supports the following SMB 2.0 functionality:
- Durable handles
Enables clients to transparently reconnect to disconnected SMB sessions after short network outages. For example, LIF failovers, LIF moves, and LIF migrations are transparent and nondisruptive for SMB 2.0 connections. NFS and CIFS in Clustered DATA ONTAP
- Compounded operations
Provides a method for combining multiple SMB messages into a single network transmission request for submission to the underlying transport.
- Asynchronous operations
Certain SMB commands from the clients can take a longer time for the server to process. For these commands, the CIFS server can send responses asynchronously.
- Increased read and write buffer sizes
Allows for better throughput across faster networks, even those with high latency.
- Increased scalability
SMB 2.0 has increased limits for number of CIFS sessions, open share connections, and open file connections.
- Increased SMB signing security
Support for stronger data integrity protection through the use of the HMAC-SHA256 hash algorithm.
Data ONTAP does not support the following SMB 2.0 functionality:
- Symbolic links
- Credit system for flow control
Supported SMB 2.1 Functionalities
- Lease oplocks
Data ONTAP uses SMB 2.1 lease oplocks, which is a new client oplock leasing model that provides advantages over traditional oplocks. Lease oplocks offer more flexibility and levels in controlling the client caching. This results in significant performance improvement in high-latency and erratic networks.
- BranchCache version 1
BranchCache is a feature that delivers WAN bandwidth optimization and improved file access performance using client-side caching at remote offices. SMB 2.1 has the functional extensions needed to manage content hashes, which are used by BranchCache-enabled CIFS servers to provide clients with information about cached content.
Data ONTAP does not support the following SMB 2.1 functionality:
- Large MTU
- Resilient handles
Supported SMB 3.0 Functionalities
- Continuously available share property
A new share property that, along with persistent handles, allows SMB clients that are connected to shares that are configured to use the continuously available share property to transparently reconnect to a CIFS server following disruptive events such as failover and giveback operations.
- Persistent handles
Enables clients to transparently reconnect to disconnected SMB sessions after certain disruptive events. A persistent handle is preserved after a disconnection. Persistent handles block other file opens while waiting for a reconnection. Along with the continuously available share property, persistent handles provide support for certain nondisruptive operations.
- Remote VSS for SMB shares
Remote VSS (Volume Shadow Copy Service) for SMB provides the functionality that allows VSS-enabled backup services to create application-consistent volume shadow copies of VSS-aware applications that access data stored over SMB 3.0 shares.
Enables a CIFS server providing SMB shares to Hyper-V servers to promptly notify the Hyper-V servers about network failures.
- ODX copy offload
ODX enables data transfers within or between ODX-enabled storage servers without transferring the data through the Windows client.
- BranchCache version 2
Provides enhanced functionality, including smaller, variable-sized content segments, which increases the reuse of existing cached content.
Data ONTAP does not support the following SMB 3.0 functionality:
- SMB Multichannel
- SMB Direct
- SMB Directory Leasing
- SMB Encryption
In addition to pNFS, NFSv4.1 provides:
Directory Delegation and Notifications
access control lists and discretionary access control
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