There are two types of Azure disks: managed disks and unmanaged disks. Before Azure managed disks, users had to create storage accounts to use unmanaged disks. A storage account might exceed the scalability target (https://docs.microsoft.com/en-us/azure/storage/common/storage-scalability-targets) and impact the performance of I/O. With managed disks, we don't need to create storage accounts by ourselves; Azure manages the accounts behind the scene. There are different types of performance tiers: standard HDD disks, standard SSD disks, and Premium SSD disks. HDD disks (https://en.wikipedia.org/wiki/Hard_disk_drive) are a cost-effective option, while SSDs (https://en.wikipedia.org/wiki/Solid-state_drive) have better performance. For an I/O-intensive workload, the Premium tier is the best option. With premium SSD disks attaching to the VM, the VM can reach up to 80,000 IOPS and 2,000 MB/s for disk throughput. Azure disks also offer four types of replication:

• Locally-Redundant Storage (LRS): Data is only persisted in one single zone
• Zone-Redundant Storage (ZRS): Data is persisted across three zones
• Geo-Redundant Storage (GRS): Cross-regional replication
• Read-Access Geo-Redundant Storage (RA-GRS): Cross-regional replication with read replica