Dell EMC Unity: Performance issues during peak hours when used with DaaS (Desktop as a service). (User Correctable)

Summary: This article describes one of the causes of performance issues when using CIFS sharing with DaaS (Desktop as a service) or VDI.

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
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Symptoms

  • Performance issues occur when everyone is trying to log in at the same time, such as at the start of the work day.

  • SMB threads are consumed a lot in the event of performance delays.

  • When we take the network trace file at the time of the event, the SETINFO (rename) operation is taking longer than other SMB operations.

  • There have been cases where these events have been reported when Microsoft teams files are placed on a share.
    (The application's behavior will cause many renaming operations.)

 

Cause

One of the reasons for this is that there is more IO during peak hours than during normal hours.

When Dell EMC Unity requests the client to release the Directory Lease, it may lead to performance delays if the client does not respond immediately.

In the current code, renaming operation is serialized on a per-file-system basis, so if one rename operation takes a long time, other rename operations will have to wait.

 

Resolution

  • In the case of a high-load system, the event can be mitigated by dividing the NAS Server and Filesystem.

  • In the case described here, the event was mitigated by disabling the Directory Leasing feature.
     

How to disable the Directory lease feature

  1. Command to check the current settings:
    svc_nas ALL -param -facility cifs -info smb2.capabilities -verbose

  2. Command to disable Directory Leasing feature ** 0x00000020(=32) => Directory lease support
    svc_nas ALL -param -facility cifs -m smb2.capabilities -v 95

  3. Command to enable (revert to Default) the Directory Leasing feature
    svc_nas ALL -param -facility cifs -m smb2.capabilities -v 127

    Note: The command will reflect the settings immediately, but the new settings will be applied in communication with the client at the timing of the next new   negotiation with the client.
    To force the configuration to be applied to all existing clients, restart the target NAS Server with the following command.
    svc_nas <NAS server> -restart

 

  • The improvement for the following events is included in Unity OE 5.1.3.
    Storage - File Performance slowdown on CIFS access may occur if a large number of rename operations are performed in parallel on the same file system.

 

Additional Information

For another case example, please refer to the following KB.

Dell EMC Unity: Write performance issue in robocopy when using CA (User Correctable)
https://www.dell.com/support/kbdoc/en-us/000186577/write-performance-issue-in-robocopy-when-using-ca-continuous-availability

Affected Products

Dell Unity 300, Dell EMC Unity 300F, Dell EMC Unity 350F, Dell EMC Unity 400, Dell EMC Unity 400F, Dell EMC Unity 450F, Dell EMC Unity 500, Dell EMC Unity 500F, Dell EMC Unity 550F, Dell EMC Unity 600

Products

Dell EMC Unity XT 380, Dell EMC Unity XT 380F, Dell EMC Unity XT 480, Dell EMC Unity XT 480F, Dell EMC Unity 600F, Dell EMC Unity 650F, Dell EMC Unity XT 680, Dell EMC Unity XT 680F, Dell EMC Unity XT 880, Dell EMC Unity XT 880F , Dell EMC Unity Family |Dell EMC Unity All Flash, Dell EMC Unity Family, Dell EMC Unity Hybrid, Dell EMC UnityVSA Professional Edition/Unity Cloud Edition ...
Article Properties
Article Number: 000193296
Article Type: Solution
Last Modified: 30 Nov 2022
Version:  6
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