PowerScale: Create a cascaded replication properly on OneFS

Summary: Below are steps to properly configure cascaded replication between Cluster_A, Cluster_B, and Cluster_C.

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Instructions

The main idea to keep in mind while configuring a cascaded replication. Ensure that replication job A_B should finish with "success/needs_attention" before starting replication job B_C.

Always, we should avoid that replication job A_B status is "failed OR canceled OR running OR paused" while replication job B_C starts.

In order to reach the above conditions:
 

  1. We can make the replication policy from A_B to create a target snapshot with the name pattern "Archive-%{SrcCluster}-%{PolicyName}-%Y-%m-%d_%H-%M-%S" when the job is finished with success.

    Cluster_A# isi sync policies create --name=A_B --source-root-path=/ifs/folder_A --target-host=xxx.xxx.xxx.xxx --target-path=/ifs/folder_B --action=sync --target-snapshot-archive=yes --target-snapshot-pattern=Archive-%{SrcCluster}-%{PolicyName}-%Y-%m-%d_%H-%M-%S --target-snapshot-expiration=5D

 

NOTE: Target snapshot cannot have an SIQ- prefix. Use "SIQ_" or "Archive-" as shown in the example above:

 

--target-snapshot-pattern=Archive-%{SrcCluster}-%

  1. Then we make the replication policy from B_C to start only when a source snapshot pattern "Archive-*" is created.

    Cluster_B# isi sync policies create --name=B_C --source-root-path=/ifs/folder_B --target-host=xxx.xxx.xxx.xxx --target-path=/ifs/folder_C --action=sync --schedule=when-snapshot-taken --snapshot-sync-pattern="Archive-*" --snapshot-sync-existing=yes


    This will guarantee that the B_C replication job starts only after A_B replication job completes with success + the B_C schedule is tied to the A_B schedule.

    Check below from LAB:

    Cluster_A# cd /ifs/folder_A
    Cluster_A# ls -lh
    total 10249
    -rw-r--r--    1 root  wheel    10M Jul 14 20:51 file
    Cluster_A# isi sync jobs start A_B
    Cluster_A# isi sync reports list
    Policy Name  Job ID  Start Time          End Time            Action  State
    -----------------------------------------------------------------------------
    A_B          1       2021-07-14T20:51:22 2021-07-14T20:51:31 run     finished
    -----------------------------------------------------------------------------
    Total: 1

    Cluster_B# cd /ifs/folder_B
    Cluster_B# ls -lh
    total 10249
    -rw-r--r--    1 root  wheel    10M Jul 14 20:51 file
    Cluster_B# isi sync reports list
    Policy Name  Job ID  Start Time          End Time            Action  State
    -----------------------------------------------------------------------------
    B_C          2       2021-07-14T20:51:51 2021-07-14T20:52:10 run     finished
    B_C          1       2021-07-14T20:51:32 2021-07-14T20:51:38 run     finished
    -----------------------------------------------------------------------------
    Total: 2

    Cluster_C# cd /ifs/folder_C
    Cluster_C# ls -lh
    total 10249
    -rw-r--r--     1 root  wheel    10M Jul 14 20:51 file
     
NOTE:
  1. The cascaded replication is one-way replication and right in specific workflows and in migrations. 
  2. Failover and Failback is ONLY SUPPORTED between Cluster A and Cluster B. Failover between B and C is NOT SUPPORTED due to target overlap on cluster B.
  3. On Failover to cluster B, the schedule must be modified to support replication from B back to A.

Affected Products

Isilon, PowerScale OneFS, Isilon SyncIQ
Article Properties
Article Number: 000189650
Article Type: How To
Last Modified: 07 أبريل 2026
Version:  8
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