Dell EMC Unity: CIFS performance issue when Continuous Availability is enabled on CIFS share [Customer correctable]
Summary: If users enables continuous availability on a CIFS file share, they may experience reduced performance as compared to general-purpose file shares with CIFS clients that support SMB3.0 or the higher dialects. ...
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Symptoms
If users enables continuous availability on a CIFS file share, they may experience reduced performance as compared to general-purpose file shares with CIFS clients that support SMB3.0 or the higher dialects.
The performance may be worse when sync replication is also enabled on the file system from which the CIFS share is exported.
The performance may be worse when sync replication is also enabled on the file system from which the CIFS share is exported.
Cause
Scale-Out File Server was introduced in Windows Server 2012. Scale-Out File Server is designed to provide scale-out file shares that are continuously available for file-based server application storage.
Scale-Out file shares provide the ability to share the same folder from multiple nodes of the same cluster. This is achieved by leveraging new Windows Server Failover Clustering features and the capabilities of the Windows file server protocol, SMB 3.0.
Continuous availability is one of the needed new features. It requires that data write through to the disk (without buffering) to ensure integrity in the event of a failure of a cluster node in a Scale-Out File Server. Actions like Folder Redirection, Offline Files, Roaming User Profiles, and other actions can generate a large number of writes that must be immediately written to disk, so it reduces the performance as compared to general-purpose file shares.
If sync replication is enabled on the file system, each write operation is required to be finished on both the source array and the destination array before returning to the upper layer. Hence when both CA and sync replication are enabled, the more severe performance impact is expected.
Scale-Out file shares provide the ability to share the same folder from multiple nodes of the same cluster. This is achieved by leveraging new Windows Server Failover Clustering features and the capabilities of the Windows file server protocol, SMB 3.0.
Continuous availability is one of the needed new features. It requires that data write through to the disk (without buffering) to ensure integrity in the event of a failure of a cluster node in a Scale-Out File Server. Actions like Folder Redirection, Offline Files, Roaming User Profiles, and other actions can generate a large number of writes that must be immediately written to disk, so it reduces the performance as compared to general-purpose file shares.
If sync replication is enabled on the file system, each write operation is required to be finished on both the source array and the destination array before returning to the upper layer. Hence when both CA and sync replication are enabled, the more severe performance impact is expected.
Resolution
This performance impact is by design. But we can turn off continuous availability feature on Unisphere if you don't need it.
Additional Information
You can use a Scale-Out File Server if you are interested in the scalability and simplicity that it offers. And You should not use Scale-Out File Server if your workload generates a high number of metadata operations, such as opening files, closing files, creating new files, or renaming existing files.
Refer to " https://docs.microsoft.com/en-us/windows-server/failover-clustering/sofs-overview " for details.
Refer to " https://docs.microsoft.com/en-us/windows-server/failover-clustering/sofs-overview " for details.
Videos
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Products
Dell EMC Unity Family |Dell EMC Unity All Flash, Dell EMC Unity Family, Dell EMC Unity Hybrid, Dell EMC UnityVSA Professional Edition/Unity Cloud EditionArticle Properties
Article Number: 000184848
Article Type: Solution
Last Modified: 01 Apr 2021
Version: 2
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