An issue that comes up repeatedly when building cloud-hosted virtual infrastructures is storage. While technologies like Azure BLOBs can be used to replicate much of what is done with disks, they miss some key features, especially those needed to build large storage appliances.
Microsoft’s upcoming cloud-hosted storage area network, Azure Elastic SAN, could solve this issue and help make a business’s last few on-premises applications cloud-ready. In this report, learn more about Microsoft’s recent preview launch of Azure Elastic SAN and how this technology promises new support for hybrid infrastructure and cloud migration initiatives.
Benefits of a cloud-native SAN
For on-premises data and systems, businesses are likely to use a storage area network to handle block-level storage at scale. They’re fast and reliable and make it easy to manage many volumes and their underlying disk hardware. Unfortunately for organizations that want to lift and shift applications based around SANs to the cloud, that functionality is hard to find. Most cloud storage is either object or file-based, with some block storage tied to physical servers through directly connected solid-state drives or hard disk drives.
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Yes, businesses could build their own software layer to manage those individual disks, but that approach isn’t economical and can add significant overhead to transactions. What’s more, they’re now requiring specific hardware allocations, negating the advantages of the cloud’s scale and treating it as just another bare metal data center.
There are a lot of applications with a lot of data that relies on SANs for storage. Without some sort of cloud storage network, they’re applications that are going to stay on-premises, where there’s less elasticity and on-demand infrastructure for services like Azure.
It’s a big gap that’s hard for cloud infrastructure to fill, and while it was already possible to use services like Azure ExpressRoute to connect Azure resources to on-premises storage arrays, users remained unable to use the cloud to add resilience, burst capabilities and global reach to their code. Cloud SAN solutions like Azure Elastic SAN fill in this functional gap.
Introducing Azure Elastic SAN
Azure Elastic SAN, touted as the first fully managed SAN in the cloud, is designed to bring at-scale block storage to cloud applications. Available as a top-level Arm (Azure Resource Manager) resource, businesses can use Azure’s infrastructure-as-code tools to make Elastic SAN part of their application virtual infrastructure, defining it and deploying it along with the rest of a virtual infrastructure.
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Azure Elastic SAN is best thought of as a virtual appliance that comprises various Azure services. Once an Elastic SAN instance has been created, IT staff can create and manage both volume groups and storage volumes, with policies to control how volumes are accessed and managed.
Once configured, Elastic SAN volumes are exposed over iSCSI, so virtual servers can access them directly using a familiar protocol that’s supported by both Windows Server and Linux. Not all iSCSI commands are supported but shouldn’t prevent a connection from working. However, the few that are yet to be supported could affect some edge cases; for example, businesses may be limited to only one connection per session.
Microsoft Azure Elastic SAN features
iSCSI support is probably the most important feature of Elastic SAN. It’s what gives it both backward compatibility with existing applications and allows users to get at-scale block-level access to storage. It doesn’t matter what the underlying technology in the store is, whether it’s a physical disk or an Azure BLOB with a block-level interface, as long as users can connect to it over iSCSI. There’s support for containers as well as for virtual machines, so iSCSI can be used with Kubernetes and other distributed application platforms.
Another important part of configuring Elastic SAN, users are able to provision the available input/output operations per second, the rate at which a system can handle tasks, as well as the service throughput. Businesses can also take advantage of Azure’s global reach to implement Zonal Redundant Storage, with storage replicated across three zones in a single Azure region, adding additional high-availability features to ensure service operation in the event of a zone outage.
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Performance with Elastic SAN can be impressive: It scales to millions of IOPs with significant throughput. Each individual volume can have up to 64,000 IOPs, and as iSCSI bypasses the limitations of standard Azure VM storage, it’s possible to get much higher performance than from other Azure storage options.
Pricing for the preview is designed to show how to provision the service, first buying core functionality with both storage and performance and then adding on additional capacity as needed. This approach allows businesses to upgrade speed in lockstep with storage, or, where there is enough performance power, to simply add volumes to gain more disk space without needing additional network capacity. It’s also a way of managing cost, paying only for the performance needed and then adding storage as required.
Designing an Elastic SAN instance
This approach helps when planning an Elastic SAN implementation: Start by working out how much storage is needed and how much performance will be required. Businesses can then mix and match base capacity and additional storage to get the mix of capacity and speed their applications need. Once the total is configured, businesses can then split this into logical volumes, with performance determined by the amount of storage in the volume and capped by the overall limits of the SAN.
For example, two or three small volumes can operate at full speed if their total requirements are below the maximum speed of the SAN. Add another two or three, and the system will automatically split its performance across all the volumes.
Volumes can be grouped into volume groups. This approach lets users apply the same policies to all the volumes in a group, for example, ensuring access only from one Azure VNet. By locking access down to a VNet associated with a specific virtual infrastructure, users can automatically limit access to a specific application, as Azure best practices suggest using application-specific virtual infrastructures. For additional security, all data is automatically encrypted at rest using BitLocker-like storage service encryption with Microsoft-managed keys.
Configuring an Elastic SAN instance
Configuration is relatively simple, especially if a business has deployed an on-premises SAN in the past. Once in the preview, users can create a new Elastic SAN instance from the Azure Portal or the command-line interface. Make sure it’s in the same region as a VNet and any compute resources needing to be used.
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Start by setting base capacity and then adding any additional storage. Once the SAN has been defined, create the first volume groups; then, add volumes, specifying how much capacity is desired in each volume. Users can now create the SAN and connect to it from an application’s virtual servers.
Why should you use Microsoft Azure Elastic SAN?
One advantage of a service like Elastic SAN is that businesses can provision a SAN and then share its storage across multiple applications. So, for example, a single instance can be used as storage for all line-of-business applications in the cloud, much like an on-premises SAN.
With cloud performance and scalability, as well as the behaviors on-premises applications need, Azure Elastic SAN could be the tool needed for the last applications in a business’s cloud migration plan. It could also be the right solution for using Azure as a highly resilient disaster recovery platform.
Although Azure Elastic SAN is only in preview format currently, prospective users can try out the tool now by downloading it from the Microsoft Azure website. Once users are enrolled in the preview program, they can begin managing and using Elastic SAN with the Azure Portal, PowerShell, a CLI, Arm and software development kits.
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