Disk redundancy options

Redundancy refers to the number of copies of data that are available at any time. This supports the failure of copies and ensures the continuity of services depending on the redundancy option chosen. Regardless of the option, data is replicated three times in a storage account for the primary region.

In Chapter 6, Understanding and Managing Storage, we discussed the various redundancy options available in Azure, and the way replication occurs between data centers. You are encouraged to go over this material again.

Azure offers both LRS and zone-redundant storage (ZRS) for managed disks, with ZRS naturally providing higher availability than LRS. ZRS is only supported for premium SSD disks and standard SSD disks. It is also only available for limited regions (currently West US 2, West Europe, North Europe, and France Central). ZRS also cannot be used with Azure Backup or Azure Site Recovery.

Understanding Azure VMs

A VM is a logical configuration of resources to emulate a machine that runs in a similar fashion to a normal computer. The difference is that you can leverage a set of pooled resources, such as memory, CPU, and storage, to create customized VMs. Typically, a physical machine is limited by its physical specifications and is designed to run a single machine. Through virtualization, though, we can carve up the resources to create several machines in accordance with the limits of our physical resources. Being able to leverage a hyperscale hypervisor such as Azure, you benefit from being able to leverage the nearly unlimited resources that Microsoft builds into its data centers to allow massive scale. You basically need to identify the number and size of resources you need and select an appropriate VM that matches your requirements.

You can run both Windows VMs as well as Linux VMs in Azure. VMs come in all sorts of sizes and a variety of prices, ranging from VMs with a small amount of memory and processing power for general purposes to large VMs that can be used for Graphics Processing Unit (GPU)-intensive and high-performance computing workloads. To createa VM, you can choose from several predefined images. There are images available for operating systems such as Windows Server or Linux, as well as predefined applications, such as SQL Server images and complete farms, which consist of multiple VMs that can be deployed at once. An example of a farm is a three-tier SharePoint farm. VMs can be created and managed either from the Azure portal, PowerShell, or the CLI, and they come in the following series and sizes.