DFS Failover Configuration Procedures

Introduction

This article outlines the steps required for Configuring your Eyeglass VM and PowerScale OneFS Clusters for DFS Failover.

Configuration Steps

1. Configure PowerScale OneFS SmartConnect Zones

   Configure DFS Folder Targets using UNC paths that reference the Primary and Secondary SMB Shares by their SmartConnect Zone names. If the PowerScale OneFS clusters do not already have SmartConnect Zone names configured, you will need to set them up.

2. Configure PowerScale OneFS SyncIQ Policies and Shares

   Create the necessary SyncIQ policies and shares to protect and access your data if they do not already exist.

   Design Considerations

   • A single SyncIQ policy can include multiple DFS targets within its file system path.
   • All DFS targets under a single SyncIQ policy will failover together.
   • To enable per-application failover, create a separate SyncIQ policy for each DFS target.

3. Configure DFS Root

   Set up a domain-based DFS root for higher availability, ensuring that the DFS root is replicated between domain controllers.

4. Create DFS Folder

   Create the DFS folder as needed for your deployment.

5. Configure DFS Target (Primary Cluster)

   Configure the DFS Target for the Primary cluster, which is currently active. To achieve this, add the UNC path to the share created on the Primary cluster, ensuring it uses a SmartConnect Zone on the Primary cluster.

   Example: \\production.example.com\SMBshare1

6. Verify Client Access

   Check access from a DFS-enabled client to ensure they have read/write access to the Primary cluster as per the configured DFS Folder(s) and Target(s).

   important

   Use the fully qualified Active Directory domain DNS name in the path. Example: \\ad1.test\DFSRoot\ShareFolder.

   Install the necessary tools on test machines to help debug and plan DFS before going into production. These tools can be found here: "Where to find DFSUTIL.EXE for Windows Server".

   Verify that the SMB client is accessing the DFS target folder’s SMB Share from the primary cluster using the following DFS utility commands (DFS client utilities must be installed as they are not standard tools):

     - dfsutil cache referral (ensure both targets are listed)

     - dfsutil cache referral flush (clear the cache for debugging)

     - dfsutil diag viewdfspath \\domainname\dfsroot\dfsfolder

   Example Commands and Output:

   
   C:\Windows\system32>dfsutil cache referral
   
   
   
   4 entries...
   
   
   
   Entry: \DFS-SVR-01\dfs02\folder2
   
   ShortEntry: \DFS-SVR-01\dfs02\folder2
   
   Expires in 270 seconds
   
   UseCount: 1 Type:0x1 ( DFS )
   
      0:[\cluster11-z01.ad1.test\SMB-Share-002] AccessStatus: 0 ( ACTIVE TARGETSET )
   
      1:[\cluster12-z01.ad1.test\SMB-Share-002] AccessStatus: 0xc00000cc ( TARGETSET )
   
   
   
   Entry: \ad1.test\dfs02
   
   ShortEntry: \ad1.test\dfs02
   
   Expires in 270 seconds
   
   UseCount: 0 Type:0x81 ( REFERRAL_SVC DFS )
   
      0:[\DFS-SVR-01\dfs02] AccessStatus: 0 ( ACTIVE TARGETSET )
   
   
   
   Entry: \AD1.test\sysvol
   
   ShortEntry: \AD1.test\sysvol
   
   Expires in 0 seconds
   
   UseCount: 0 Type:0x1 ( DFS )
   
      0:[\ad1.AD1.test\sysvol] AccessStatus: 0 ( ACTIVE TARGETSET )
   
   
   
   Entry: \DFS-SVR-01\dfs02
   
   ShortEntry: \DFS-SVR-01\dfs02
   
   Expires in 270 seconds
   
   UseCount: 0 Type:0x81 ( REFERRAL_SVC DFS )
   
      0:[\DFS-SVR-01\dfs02] AccessStatus: 0 ( ACTIVE TARGETSET )
   
   
   
   DfsUtil command completed successfully.
   
   
   
   C:\Windows\system32>dfsutil diag viewdfspath \\ad1.test\dfs02\folder2
   
   
   
   The DFS Path <\\ad1.test\dfs02\folder2> resolves to -> <\\production.example.com\SMBshare1>
   
   
   
   Done processing this command.
   

7. Eyeglass Setup

   1. Install Eyeglass

      Install Eyeglass and add clusters as managed devices

   2. Initial Inventory

      Allow Eyeglass to complete initial inventory and create Eyeglass configuration replication jobs

   3. Enable DFS Mode

      Enable Eyeglass DFS mode on the Eyeglass Configuration Replication Jobs for the SyncIQ policies that will use the Eyeglass DFS Failover solution.

      note

      If a SyncIQ policy has already been failed over in PowerScale OneFS and a mirror policy exists, enable Eyeglass DFS Mode for both the active and disabled policies.

   4. Monitor AUTODFS Jobs

      DFS-enabled SyncIQ policies will appear in a new folder and be labeled as AUTODFS.

      Initially, the state of the Eyeglass AUTODFS job will be pending. After the next configuration replication cycle and the new DFS job has run, the state will update to OK if no errors were encountered.

      important

      With Eyeglass DFS mode, SMB shares only exist on the active cluster. This setup will not interfere with failover. If Eyeglass detects that the share exists on the standby cluster, it will delete it on the current SyncIQ target (read-only) cluster.

      If the SyncIQ policy associated with an Eyeglass DFS mode (AUTODFS) job is renamed, Eyeglass will consider it a new job and create it as a regular Eyeglass Configuration Replication (AUTO) job. You must re-enable DFS for this job.

8. Configure DFS Target (Secondary Cluster)

   1. Configure DFS Target

      Configure the DFS Target for the Secondary cluster (the cluster that is NOT currently active) by adding the UNC path to the share created on the Secondary cluster. Ensure this UNC path uses a SmartConnect Zone on the Secondary cluster.

      Example: \\dr.example.com\SMBshare1

      important

      Use exactly the same share name as was used for the Primary cluster DFS target.

   2. Verify DFS Targets

      Confirm that both DFS Targets for the Primary and Secondary clusters are enabled.

      Design Consideration

      Folder Targets:

      • Configure Folder Targets with UNC Paths to the Primary and Secondary SMB Shares using their SmartConnect Zone names.

      With Eyeglass DFS mode, the shares only exist on one cluster at a time. You must create both target UNC paths in DFS folder targets. Adding the target cluster will not detect the site information since the share does not exist. This is acceptable and will not interfere with failover.

      Set Target Folder Priorities:

      • Primary Cluster: Set as the first priority among all targets.

      • Secondary Cluster: Set as the last priority among all targets.

9. Verify Client Access

   Check access from a DFS-enabled client to ensure they have read/write access enabled to the Primary cluster only, as configured in the DFS Folders and Targets.

   important

   Use the fully qualified Active Directory domain DNS name in the path.

   Example: \\ad1.test\DFSRoot\ShareFolder.

   1. Verify DFS Folder Target Paths

      Ensure the DFS folder target paths provide access to both the Primary and Secondary Cluster’s SMB Shares.

      Note: Only the SMB Share on the Primary Cluster is active before failover. The SMB Share on the Secondary Cluster is created for DFS Folder Target creation but deleted after registration.

   2. Check SMB Client Access

      Verify that the SMB client accesses the DFS target folder’s SMB Share from the primary cluster, even though a DFS target for the Secondary cluster exists.

   3. Use DFS Utility Commands

      Ensure DFS client utilities are installed on the OS. They are not standard tools.

      Commands:

      • dfsutil cache referral (ensure both targets are listed)
      • dfsutil cache referral flush (clear the cache for debugging)
      • dfsutil diag viewdfspath \\domainname\dfsroot\dfsfolder

      Example Commands and Output:

      
      C:\Windows\system32>dfsutil cache referral
      
      
      
      4 entries...
      
      
      
      Entry: \DFS-SVR-01\dfs02\folder2
      
      ShortEntry: \DFS-SVR-01\dfs02\folder2
      
      Expires in 270 seconds
      
      UseCount: 1 Type:0x1 ( DFS )
      
         0:[\cluster11-z01.ad1.test\SMB-Share-002] AccessStatus: 0 ( ACTIVE TARGETSET )
      
         1:[\cluster12-z01.ad1.test\SMB-Share-002] AccessStatus: 0xc00000cc ( TARGETSET )
      
      
      
      Entry: \ad1.test\dfs02
      
      ShortEntry: \ad1.test\dfs02
      
      Expires in 270 seconds
      
      UseCount: 0 Type:0x81 ( REFERRAL_SVC DFS )
      
         0:[\DFS-SVR-01\dfs02] AccessStatus: 0 ( ACTIVE TARGETSET )
      
      
      
      Entry: \AD1.test\sysvol
      
      ShortEntry: \AD1.test\sysvol
      
      Expires in 0 seconds
      
      UseCount: 0 Type:0x1 ( DFS )
      
         0:[\ad1.AD1.test\sysvol] AccessStatus: 0 ( ACTIVE TARGETSET )
      
      
      
      Entry: \DFS-SVR-01\dfs02
      
      ShortEntry: \DFS-SVR-01\dfs02
      
      Expires in 270 seconds
      
      UseCount: 0 Type:0x81 ( REFERRAL_SVC DFS )
      
         0:[\DFS-SVR-01\dfs02] AccessStatus: 0 ( ACTIVE TARGETSET )
      
      DfsUtil command completed successfully.
      
      C:\Windows\system32>dfsutil diag viewdfspath \\ad1.test\dfs02\folder2
      
      The DFS Path <\\ad1.test\dfs02\folder2> resolves to -> <\\production.example.com\SMBshare1>
      
      Done processing this command.
      

Next Steps

You may now go to the main DFS Failover Article to execute the procedure.