An enterprise designs a disaster recovery (DR) solution for a critical financial applicati… — Microsoft Azure Solutions Architect (AZ-305)

An enterprise designs a disaster recovery (DR) solution for a critical financial application hosted on Azure virtual machines (VMs) in the East US region, with West US as the target DR region.

The application architecture consists of:
* Two application tier VMs ( $AppVM1$ and $AppVM2$ ). Each VM has a write churn rate of $1\text{ MB/s}$ .
* Two database tier VMs ( $DBVM1$ and $DBVM2$ ) running SQL Server. Each database VM has three Premium SSD disks: a data disk with $8\text{ MB/s}$ write churn, a transaction log disk with $25\text{ MB/s}$ write churn, and a TempDB disk with $15\text{ MB/s}$ write churn.

The business requirements specify:
* The application tier requires a Recovery Point Objective (RPO) of $2\text{ hours}$ and a Recovery Time Objective (RTO) of $4\text{ hours}$ .
* The database tier requires an RPO of $10\text{ seconds}$ and an RTO of $10\text{ minutes}$ .

Which two actions should you include in the disaster recovery design?

Replicate the application tier VMs (AppVM1 and AppVM2) to the West US region by using Azure Site Recovery.Answer
Configure SQL Server Always On Availability Groups to replicate the databases from the East US region to target SQL Server VMs in the West US region.Answer
C
Replicate the database tier VMs (DBVM1 and DBVM2) to the West US region by using Azure Site Recovery.
D
Configure the database VMs to write backups to a Read-Access Geo-Redundant Storage (RA-GRS) account and perform write operations directly to the secondary storage endpoint in West US during a failover.

Answer

Replicating the application tier VMs with Azure Site Recovery and configuring SQL Server Always On Availability Groups for the database tier.

The correct design uses Azure Site Recovery to replicate the application VMs since their RPO and churn fit within ASR's capability envelope. For the database tier, native SQL Server Always On Availability Groups are required because the

10\text{-second}

RPO cannot be met by ASR, and the transaction log disk's write churn of

25\text{ MB/s}

exceeds standard ASR limits.

Step-by-Step Solution

Analyze the database tier constraints.

The database VMs require a 10-second RPO and have a transaction log write churn of

25\text{ MB/s}

Identify if Azure Site Recovery can support the database tier requirements.

Evaluate Azure Site Recovery limits and capabilities.

Azure Site Recovery cannot support a 10-second RPO (standard RPO is higher) and the

25\text{ MB/s}

log disk write churn exceeds the standard Premium SSD per-disk replication limit of

10\text{ MB/s}

. Thus, ASR cannot be used for the database tier.

Compare database requirements against Azure Site Recovery service limitations.

Select database-native replication tools.

SQL Server Always On Availability Groups should be configured for the database tier to achieve near-real-time asynchronous replication and support the 10-second RPO.

Meet database RPO and bypass Azure Site Recovery write churn constraints.

Evaluate the application tier constraints.

The application tier requires a 2-hour RPO and has

1\text{ MB/s}

write churn, which is well within Azure Site Recovery thresholds.

Determine the appropriate DR mechanism for the application tier VMs.

Key Concept

Designing hybrid replication strategies using Azure Site Recovery and database-native replication tools based on write churn limits and RPO constraints.

Question

Answer

Step-by-Step Solution

Key Concept

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