Today, I would like to discuss a subject that all my clients asking me about: Managed Disks vs. Storage accounts. Should you make the move or not?
Managed disks support only LRS (Locally redundant storage). If you require to replicate the data to another geographical location…. It’s a no for the moment.
If you need access to the VHD using Azure Storage Explorer – Not available as yet.
If LRS (3 copies of your data in the same data centre) let you sleep well enough at night, you should consider moving to Managed Disks. There are some really good features that simplifying VM’s deployments and management. Let’s have a look at some:
You don’t have to worry about limitations of storage accounts IOP’s. You don’t need to move VHD’s from one account to another due to slow performance. Azure manage it all for you. All you have to do, is to choose Standard or Premium storage and disk size, and you are good to go.
Probably the single most important advantage is that Azure infrastructure will make sure that disk in Availability Sets will run on separate stamps. (A stamp is a physical storage unit in Azure). With un-managed disks, you have to make sure that you storage accounts running on separate stamps by yourself. It can be a tricky task, as you have no control on which stamp your storage account is created. Quiet often I had to create and delete storage accounts multiple time, until I got lucky and Azure fabric was kind enough to me and created the storage account on a new stamp.
I did see some installations of availability groups with multiple VM’s all using the same storage stamp – not a good outcome if the stamp itself goes offline.
Although, snapshots are available on storage accounts, it is complicated to manage and require the usage of PowerShell or Azure Storage Explorer. The management of snapshot of managed disk can be done via the Azure portal. It is a quick and simple operation (as it should be)! I hope that incremental snapshots will be available in the future.
Managed Disk and snapshot being displaying as an asset in the portal makes it easier to manage it.
Currently, you cannot backup VM’s with managed disks to Azure Recovery service. It is coming soon though!
I hope that information can help you decide what type of storage is appropriate for your VM’s.
Good bye for now. See you all next week.