Remote Replication – QSAN White Paper

This article summarizes QSAN Remote Replication for disaster recovery, covering synchronous and asynchronous modes, theory of operation, configuration, supported topologies, and best practices.

Download: Remote Replication PDF

Click here to download the Remote Replication White Paper.

Key Sections:

  • Introduction: DR concepts, RPO and RTO, and why replication protects business continuity.
  • Synchronous vs. Asynchronous: Zero-loss sync (RPO=0; link latency <10 ms, ~<100 km) vs. scheduled async (snapshot-based increments; RPO/RTO depend on interval).
  • Support Firmware Version: XEVO 2.1.0+ (sync license; 2.1.1 adds local-to-remote); SANOS 2.0.0+ (sync license; 2.0.1 adds local-to-remote).
  • Theory of Operation:
    • Synchronous: full copy, fracture log tracks out-of-sync blocks and resyncs after interruption.
    • Asynchronous: full copy, then snapshot-based incremental transfers; requires adequate snapshot space.
    • Auto Configuration: source pushes volume configs to target to auto-create volumes (XEVO only).
    • Traffic Shaping: peak/off-peak bandwidth groups (eight groups).
    • MPIO: up to 2 paths per replication task for redundancy.
    • MC/S: up to 4 connections per task path to increase throughput.
    • Local Clone → Remote: disk roaming method to avoid long first full copy; then switch to remote replication.
    • Support Scenario: XCubeFAS and XCubeSAN can be source/target; auto/1-step local-to-remote features are XEVO-only.
  • Configure Remote Replication:
    • Prerequisites: per-volume max tasks = 1; per-system max tasks (sync+async) = 32; MPIO max 2; MC/S max 4.
    • License: synchronous replication requires a license (30-day trial available); activation requires reboot.
    • Manual / Auto: step-by-step setup, or XEVO auto configuration via management login.
    • Operations: resume vs. full replication; traffic shaping; enable multipath; add connections; switch local clone to remote.
  • Use Cases:
    • Topologies: one-directional, bi-directional, one-to-many, many-to-one, many-to-many (each session is one-to-one).
    • Sync Failover: manual failover to target if source is down; role switch supported.
    • Sync + C2F: write-back with Cache-to-Flash modules for integrity during power loss.
  • Conclusion & Appendix: summary; Apply To: XEVO 2.1.0+; reference: XEVO Software Manual.

Critical Notes:

  • LICENSE: Synchronous replication requires a license; a 30-day trial is provided.
  • SYNC LINK: For synchronous tasks, the source port should be ≥10 Gbps.
  • ASYNC SPACE: Ensure sufficient snapshot capacity for asynchronous increments.
  • XEVO-ONLY: Auto Replication and 1-Step Local-to-Remote require XEVO on both source and target, with management and data ports connected.
  • ONE-TO-ONE: A volume cannot be both source and target or be used for sync and async simultaneously.

JetStor Support

For assistance with remote replication on JetStor systems:
๐Ÿ“ง [email protected]
๐ŸŽซ Submit Support Ticket