DR Options for Storage on Azure

Key Considerations for Storage DR on Azure

1. Understanding RPO and RTO

Define RPO (Recovery Point Objective):
RPO determines the maximum acceptable amount of data loss in the event of a disaster. For critical workloads such as financial systems or healthcare applications, a sub-10-minute RPO is essential for near-continuous data protection.

Define RTO (Recovery Time Objective):
RTO specifies how quickly applications and services need to be restored after an outage. For business-critical applications, an RTO of minutes is often required to minimize downtime and ensure operational continuity.

Achieving Near Zero RPO:
Achieving near-zero RPO can be challenging, but it is feasible with technologies like Azure NetApp Files with cross-region replication, which employs low-latency replication strategies. These solutions require fine-tuned configurations and a high-performance infrastructure to meet the stringent requirements of critical workloads.

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2. Azure Storage DR Options

a. Overview of Azure Storage Types

• Blob Storage:
  Blob storage is an object storage solution optimized for unstructured data, including images, videos, logs, and backups. It is highly scalable and cost-effective, making it ideal for large-scale data storage needs.

• Azure Files:
  Azure Files offers fully managed CIFS/SMB file shares, suitable for workloads requiring file-level access, such as collaboration platforms or enterprise applications.

• NetApp Files:
  Azure NetApp Files supports high-performance workloads with SMB, NFS, or dual protocol support. It's designed for mission-critical applications that require high availability and performance, such as databases and SAP applications.

• Azure Disk:
  Managed Disks provide block-level storage designed for Azure VMs, offering high durability and scalability for mission-critical virtualized workloads.

b. Redundancy Options

• Blob & Files:

  • Locally Redundant Storage (LRS): Suitable for non-critical workloads where data loss in a single data center failure is acceptable.

  • Zone-Redundant Storage (ZRS): Ensures availability within a region across availability zones, providing protection against zone-level outages.

  • Geo-Redundant Storage (GRS): Provides automatic cross-region replication, ideal for applications requiring data durability across regions.

  • Read-Access Geo-Redundant Storage (RA-GRS): Offers read access in secondary regions, facilitating faster recovery.

• NetApp Files:
  NetApp’s cross-region replication (via SnapMirror technology) replicates data asynchronously across regions, enabling high availability and disaster recovery for performance-sensitive workloads.

c. When to Choose Each Option

• Blob Storage:

  • LRS: Ideal for non-critical workloads like development environments, where cost is a priority and occasional downtime is acceptable.
    RPO : Near ZERO (Sync replication)

  • ZRS: Best for regional applications needing fault tolerance at the zone level.
    RPO: Near ZERO (Sync replication)

  • GRS & RA-GRS: Suitable for business-critical workloads needing cross-region disaster recovery, with an acceptable RPO of up to 12 hours for asynchronous replication.
    RPO: 1 Hour
    SLA RPO : None (Max could be Several hours )

• Azure Files (GRS):
  Ideal for use cases like archival storage and backup systems that require cross-region replication but can tolerate a slight delay in data synchronization.
  RPO: 15 mins
  SLA RPO: None (several hours for Large Datasets)

• NetApp Files:
  High-Performance SMB/NFS File Shares: Use NetApp Files for workloads like virtual desktop infrastructures (VDI), large-scale databases, SAP applications, or high-performance computing (HPC). NetApp Files' cross-region replication is ideal for mission-critical applications requiring near-zero RPO and rapid recovery. For example, replicating SAP HANA databases or media processing workloads across regions to ensure high availability and disaster recovery. it typical replicate your data less than 10 mins based on replication schedule configuration
  RPO: 10 Min
  SLA RPO : Less than 20 Mins

• Azure Disk:
  Managed Disks are excellent for VM workloads, but to enable geo-replication, you would need to implement Azure Backup, Site Recovery or Custom Solution using Azure Disk Snapshot
  SLA RPO: One Hour

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Conclusion

Azure provides a diverse range of storage solutions that meet various disaster recovery needs, from object storage to high-performance file systems. For critical workloads requiring near-zero RPO and fast recovery, Azure NetApp Files offers the best performance and flexibility. Blob Storage and Azure Files, with Geo-Redundant Storage, provide cost-effective solutions for less critical workloads but still offer robust data durability. The right choice depends on the specific needs of the workload, including performance, cost, and recovery objectives. By selecting the appropriate Azure storage solution and configuring it correctly, organizations can ensure that their critical workloads remain highly available and resilient to disruptions.