Azure Replication for Business Continuity and Disaster Recovery

Azure Replication is a crucial aspect of business continuity and disaster recovery. It ensures that your data is safely replicated across different regions, so you can quickly recover in case of a disaster.

With Azure Replication, you can replicate data across different regions in real-time, or with a short delay. This allows you to choose the right replication strategy for your business needs.

Replicating data across regions provides a high level of availability and redundancy, reducing the risk of data loss due to a single point of failure.

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To replicate workloads on supported Azure VMs, you'll need an Azure subscription and at least 1 GB RAM in the VM. This is a prerequisite verification step.

Replication involves copying data from a source VM to a target region, which can be done using ASR (Azure Site Recovery) replication. You'll need to prepare the source VM and the target region before starting the replication process.

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The transition to a new region for Azure VMs is relatively simple, and you can discard the resources in the source region once the replication is complete.

Here's a quick rundown of the components involved in disaster recovery for Azure VMs:

To replicate your Azure VMs, you'll need to consider several architectural components.

Azure VMs in the source region can be running any supported operating system.

The source VM storage can be managed or have non-managed disks spread across storage accounts.

VMs can be located in one or more subnets in a virtual network (VNet) in the source region.

A cache storage account is required in the source network to store VM changes before sending them to target storage.

During replication, target resources are used, and when a failover occurs, these resources are used again.

Here's a summary of the components involved in disaster recovery for Azure VMs:

Make sure to check that you're able to create VMs in the target region, and that your subscription has enough resources to support VM sizes that are needed in the target region.

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Locally Redundant storage is a cost-effective option for protecting your data. It replicates data three times within one data center.

This replication ensures that your data is durable and can withstand drive failure and server rack failure. LRS provides at least 99.999999999% durability for objects during a given year.

However, LRS doesn't cover all data loss scenarios, so it's best used for less sensitive data or data that's restricted to one location due to compliance requirements.

Azure SQL Replication is a crucial tool for businesses that are moving to a pure-cloud or hybrid model. It's a top choice among enterprises that have traditionally used SQL Server on-premise.

In many cases, Azure SQL Replication is needed to synchronize distributed applications and workloads. This is especially true for globally distributed data.

To ensure disaster recovery and business continuity, Azure SQL Replication is a must-have. This is a critical aspect of any business continuity plan.

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Azure SQL Replication can also be used to scale out read-only workloads. This is particularly useful for applications that require high availability and low latency.

Here are some of the significant reasons why Azure SQL Replication is needed:

SAP Datasphere can replicate data from SAP S/4HANA to an Azure Data Lake Storage Gen2, creating a data lake that can be used for various analytics and business intelligence purposes.

Data is replicated in near real-time, allowing for timely decision-making and analysis.

To replicate data from S/4HANA to an Azure Data Lake, you need to set up a SAP Datasphere flow, which involves creating a source and target connection, defining the data replication schedule, and configuring the data transformation and mapping.

Data transformation and mapping involve converting S/4HANA data into a format that's compatible with the Azure Data Lake, which can include data type conversions and data aggregation.

By replicating data from S/4HANA to an Azure Data Lake, you can create a centralized data repository that can be used for various analytics and business intelligence purposes, such as data warehousing, data science, and business reporting.

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Replication policies are a crucial part of Azure replication, and understanding how they work is essential for a smooth replication process.

The default replication policy in Azure keeps recovery points for one day, which can be modified as you enable replication or by creating a new policy at any time.

You can manage and modify the settings of default replication policies as follows: you can modify the settings as you enable replication, or you can create a replication policy at any time and then apply it when you enable replication.

High recovery point retention periods can have implications on storage costs, as more recovery points may need to be saved.

Managing target resources is a crucial aspect of ensuring a smooth failover process. You can modify target settings as you enable replication, and the default SKU for the target region VM is the same as the SKU of the source VM.

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The dropdown list only shows relevant SKUs of the same family as the source VM, so you won't have to sift through a long list of options. This ensures that your target VM is compatible with your source VM.

You can also modify target settings after replication is already working, but be aware that some settings, like the availability type, can't be updated while replication is in progress. To change these settings, you'll need to disable replication, make the change, and then reenable.

Here are the target resource settings that can be modified after replication is working:

These settings can be updated while replication is in progress, but it's always a good idea to double-check that your changes will work as intended.

Policy plays a crucial role in Site Recovery, and it's essential to understand how it works.

You can manage and modify the settings of default replication policies as you enable replication. This means you can adjust the settings to suit your specific needs.

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By default, Site Recovery creates a new replication policy with specific settings, including a one-day recovery point retention period and app-consistent snapshot frequency set to zero hours (disabled).

High recovery point retention periods can have implications on storage costs, as more recovery points need to be saved.

Here's a summary of the default replication policy settings:

You can create a replication policy at any time and apply it when you enable replication, giving you flexibility in your configuration.

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To set up Azure Site Recovery for on-premises VMWare VMs and physical servers, you need to ensure you're running the correct versions of the VMware virtualization servers. The machines must be running supported operating systems and comply with Azure requirements like network and storage requirements.

To get started, you'll need to set up the source environment and the configuration server for coordinating communications between the on-premises infrastructure and Azure. This involves specifying the Azure subscription and network settings as part of setting up the target environment.

There are key differences in setting up ASR for VMware VMs and physical servers. For VMware VMs, the configuration server can be set up by downloading an Open Virtualization Format (OVF) template, while for physical servers, it has to be done manually by downloading the VFD file.

Here are the steps to set up Azure Site Recovery for on-premises VMWare VMs and physical servers:

Note that the configuration details for member databases in Azure SQL replication involve adding configuration details in the next section.

Crash-consistent snapshots are created every five minutes by default, but you can't modify this setting. This type of snapshot captures data on the disk at the time it's taken, but doesn't include anything in memory.

Most apps can recover well from crash-consistent points, making them sufficient for replicating operating systems and apps like DHCP servers and print servers.

To achieve multi-VM consistency, machines in the replication group communicate with each other over port 20004. Ensure there's no firewall blocking this internal communication, and manually open port 20004 on Linux VMs if necessary.

During a failover, you can use any recovery point, and the VMs are created in the target resource group, virtual network, subnet, and availability set. Quickly replicating an Azure VM to a secondary region is a key benefit of this process.

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App-Consistent snapshots contain all the information in a crash-consistent snapshot, plus all the data in memory and transactions in progress. This means they provide a more complete picture of your system's state at the time of the snapshot.

App-consistent snapshots use the Volume Shadow Copy Service (VSS) to create a copy-on-write operation on the volume. This process informs every app on the machine that it needs to flush its memory-resident data to disk before the snapshot is taken.

The Copy Only backup (VSS_BT_COPY) method used by Azure Site Recovery doesn't change Microsoft SQL's transaction log backup time and sequence number. This is important for maintaining data consistency in SQL databases.

App-consistent snapshots are more complex and take longer to complete than crash-consistent snapshots. This can affect the performance of apps running on a VM enabled for replication.

To ensure app-consistent snapshots are taken frequently enough, you should set the frequency at less than the retention period for recovery points. For example, if you retain recovery points using the default setting of 24 hours, you should set the frequency at less than 24 hours.

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During a failover, you can use any recovery point to quickly replicate an Azure VM to a secondary region. This allows for rapid recovery in the event of an outage.

The failover process creates Azure VMs in the target resource group, virtual network, subnet, and availability set. This ensures that the failed VM is quickly replaced with a functioning one.

You can initiate a failover at any time, but it's essential to verify the VM in Azure before reprotecting it for replication to the on-premises site.

Here's a quick summary of the failover process:

By understanding the failover process, you can ensure business continuity and minimize downtime in the event of an outage.