An organization is designing a disaster recovery (DR) solution from the East US region (pr… — Microsoft Azure Solutions Architect (AZ-305)

An organization is designing a disaster recovery (DR) solution from the East US region (primary) to the West US region (secondary) for a multi-tier application. The solution must achieve a Recovery Point Objective (RPO) of under $4\text{ hours}$ and a Recovery Time Objective (RTO) of under $2\text{ hours}$ for all workloads. The application consists of the following virtual machines (VMs):

1. AppVM1 (Application Tier):
- Disk 1 (OS, Premium SSD): $5\text{ MB/s}$ average write churn
- Disk 2 (Data, Premium SSD): $25\text{ MB/s}$ average write churn
- Total VM write churn: $30\text{ MB/s}$

2. DBVM1 (Database Tier running SQL Server):
- Disk 1 (OS, Premium SSD): $10\text{ MB/s}$ average write churn
- Disk 2 (Data, Premium SSD): $65\text{ MB/s}$ average write churn
- Disk 3 (Logs, Premium SSD): $45\text{ MB/s}$ average write churn
- Total VM write churn: $120\text{ MB/s}$

Which two configurations should you include in the disaster recovery design to meet the requirements while staying within supported limits?

Replicate AppVM1 to the secondary region using Azure Site Recovery with High Churn replication enabled.Answer
Configure a SQL Server Always On Availability Group with an asynchronous replica on a VM in the secondary region for the databases on DBVM1.Answer
C
Replicate DBVM1 to the secondary region using Azure Site Recovery with High Churn replication enabled.
D
Configure Azure Backup with Cross-Region Restore (CRR) for both VMs to meet the replication needs.

Answer

Replicate AppVM1 using Azure Site Recovery with High Churn replication enabled, and configure a SQL Server Always On Availability Group with an asynchronous replica in the secondary region for DBVM1.

For AppVM1, the data disk's write churn of

25\text{ MB/s}

requires the configuration of Azure Site Recovery's High Churn replication tier since it exceeds the standard limit of

20\text{ MB/s}

per disk. For DBVM1, the combined disk write churn of

120\text{ MB/s}

is above the maximum capacity threshold of

100\text{ MB/s}

for Azure Site Recovery (even with High Churn enabled). Therefore, a database-level replication method such as SQL Server Always On Availability Groups must be utilized for DBVM1 to achieve the designated objectives.

Step-by-Step Solution

Analyze the write churn for AppVM1.

AppVM1 has one disk at

25\text{ MB/s}

write churn and a total VM churn of

30\text{ MB/s}

This exceeds the standard

20\text{ MB/s}

per-disk limit for Premium SSDs but is within the

100\text{ MB/s}

per-disk and per-VM limits supported by the High Churn replication tier in Azure Site Recovery.

Analyze the write churn for DBVM1.

DBVM1 has a total VM write churn of

10\text{ MB/s} + 65\text{ MB/s} + 45\text{ MB/s} = 120\text{ MB/s}

Because the total VM write churn (

120\text{ MB/s}

) exceeds the absolute ASR support threshold of

100\text{ MB/s}

per VM, replication via ASR is not viable. An alternative application-level replication method is required.

Select the appropriate alternative replication for the database VM.

Deploy an asynchronous replica using SQL Server Always On Availability Groups on a database VM in the target region.

This offloads database replication to the native application level, bypassing virtual machine-level replication limits and successfully meeting the database RPO/RTO objectives.

Key Concept

Determining Azure Site Recovery limits and matching workloads to ASR replication tiers versus native application replication.

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic