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Proxmox - Implement Storage Replication for Disaster Recovery

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By harryvasanth
3 min read
Proxmox - Implement Storage Replication for Disaster Recovery

Intro

Disaster recovery is a critical component of maintaining business continuity in virtualized environments. Proxmox VE offers built-in storage replication features to ensure data redundancy and minimize downtime in the event of hardware or site failures. This guide explores advanced concepts in Proxmox storage replication, including ZFS-based replication, stretched clusters, and best practices for disaster recovery to help you implement a robust and efficient strategy.

Step 1: Understanding Proxmox Storage Replication

Proxmox storage replication is a feature that uses ZFS snapshots to replicate virtual machine (VM) data between nodes in a cluster. It ensures minimal data loss by synchronizing changes at regular intervals and is particularly useful for disaster recovery scenarios.

Key Features

  • Asynchronous Replication: Data is replicated periodically, reducing the impact on performance.
  • ZFS Snapshots: Uses incremental snapshots for efficient data transfer.
  • Failover Support: Enables quick recovery by promoting replicated VMs on secondary nodes.

Step 2: Preparing Your Environment

2.1 Requirements

  1. A Proxmox cluster with at least two nodes.
  2. ZFS storage configured on all nodes.
  3. Sufficient network bandwidth for replication.

2.2 Configure ZFS Storage

Ensure ZFS is installed and a pool is created on each node:

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zpool create -f rpool /dev/sdX

Verify the pool:

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zpool status

Add the ZFS pool to Proxmox via the web interface under Datacenter > Storage > Add > ZFS.

Step 3: Setting Up Storage Replication

3.1 Enable Replication

  1. Navigate to Datacenter > Replication in the Proxmox web interface.
  2. Add a new replication job:
    • Select the source VM.
    • Choose the target node.
    • Set the replication interval (e.g., every 5 minutes).

Example Command-Line Configuration:

Use pvesr to configure replication:

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pvesr create local-zfs remote-node remote-zfs --rate 100M --interval 300

This replicates data from local-zfs to remote-node’s remote-zfs every 5 minutes with a bandwidth limit of 100 MB/s.

3.2 Verify Replication Status

Check the status of replication jobs:

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pvesr status

Step 4: Stretched Clusters for Disaster Recovery

A stretched cluster spans multiple sites, ensuring high availability (HA) within and across locations.

4.1 Configure a Stretched Cluster

  1. Set up two Proxmox clusters (e.g., one per site).

  2. Use LINSTOR with DRBD® to replicate volumes across sites:

    • Install LINSTOR on all nodes:
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      apt install linstor-controller linstor-satellite linstor-client drbd-utils
    • Configure DRBD resources for synchronous replication.
  3. Add both clusters to the same Proxmox environment and configure shared storage using LINSTOR.

4.2 Benefits of Stretched Clusters

  • Reduces Recovery Point Objective (RPO) to seconds.
  • Ensures VMs can fail over seamlessly between sites.

Step 5: Testing Disaster Recovery Scenarios

5.1 Simulate Node Failure

  1. Power off the primary node hosting a replicated VM:
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    poweroff
  2. Promote the replicated VM on the secondary node:
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    qm start <VMID> --node <secondary-node>

5.2 Restore from Backup

If replication fails, restore from backups stored on a Proxmox Backup Server (PBS):

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proxmox-backup-client restore vm/<VMID> --repository <PBS-URL>

Step 6: Best Practices for Storage Replication

6.1 Optimize Bandwidth Usage

Limit replication bandwidth during peak hours:

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pvesr set <job-id> --rate 50M

6.2 Monitor Replication Jobs

Set up alerts for failed replication jobs using Prometheus or email notifications:

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cat /var/log/pve/tasks/replication.log | grep ERROR

6.3 Combine with Backups

Replication complements but does not replace backups; use PBS for periodic backups:

  • Local backups for fast recovery.
  • Remote backups for site-wide disaster recovery.

Step 7: Advanced Techniques

7.1 Snapshot Management

Use ZFS snapshots to roll back VMs in case of corruption or accidental changes:

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zfs snapshot rpool/data@backup-20230520
zfs rollback rpool/data@backup-20230520

7.2 Geographical Redundancy

Replicate VMs across geographically distributed locations using cloud providers or secondary data centers.

Example with Offsite Backup:

Use tools like rclone to sync backups to cloud storage:

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rclone sync /mnt/proxmox-backups remote:/backups/proxmox

Step 8: Monitoring and Troubleshooting

8.1 Check Logs for Errors

Review logs to diagnose issues:

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journalctl -u pvesr.service

8.2 Validate Data Integrity

Verify ZFS pool health regularly:

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zpool scrub rpool
zpool status rpool

Conclusion

Implementing storage replication in Proxmox VE enhances disaster recovery capabilities by ensuring data redundancy and minimizing downtime during failures. By leveraging features like ZFS-based replication, stretched clusters, and advanced snapshot management, you can create a robust infrastructure that meets stringent RPO and RTO requirements. Combine replication with regular backups and proactive monitoring to build a comprehensive disaster recovery strategy tailored to your needs.

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