Storage

Question 1

What are advantages of managed disks?

Answer 1

1. managed disks are AMR managed resources with RBAC whereas unmanaged disk is a vhd file residing in a storage account
2. No need to create a storage account beforehand, also storage account 20,000 IOPS limit does not apply
3. Better availability for Availability Sets - disks in different fault domains
4. Disk snapshots available

Azure disks are available as either Managed Disks or unmanaged disks. All Azure disks are backed by page blobs in Azure Storage. When you use unmanaged disks, they use an Azure Storage account in your Azure subscription, and you have to manage that account. This is particularly troublesome because there are limitations in Azure Storage, and if you have heavy disk usage, you may end up experiencing downtime due to throttling.

When you move to Managed Disks, Microsoft handles the storage account, and all storage limitations are removed. All you have to worry about is your disk. You can leave the Storage account in Microsoft’s hands.

Perhaps an even more important reason to use Managed Disks is that by doing so, you avoid a possible single point of failure in your VM. When you use unmanaged disks, there is a possibility that the Azure Storage accounts backing up your disks might exist within the same storage scale unit. If a failure occurs in that scale unit, you will lose all of your disks. By ensuring that each Managed Disk is in a separate scale unit, you avoid the situation of a single point of failure.

Question 2

What are disadvantages of managed disks?

Answer 2

1. More expensive

2. Only predefined fixed sizes (unmanaged: flexible size and you pay only what you consume)

Question 3

How can you prevent administrators from deleting data in a Blob storage container?

Answer 3

By using a time-based retention policy.

When a time-based retention policy is set, blobs can be created and read, but not modified or deleted. After the retention period has expired, blobs can be deleted but not overwritten.

https://docs.microsoft.com/en-us/azure/storage/blobs/storage-blob-immutability-policies-manage