Page Blob and its relation with Disk

Question

Hi,

I am reading about Page Blob and its relation to Azure IaaS Disk.

According to this page https://learn.microsoft.com/en-us/azure/storage/blobs/storage-blob-pageblob-overview?tabs=dotnet
Azure virtual machine disks are backed by page blobs. Azure offers two types of durable disk storage: premium and standard.

According to the documentation on Azure Managed Disk, https://learn.microsoft.com/en-us/azure/virtual-machines/managed-disks-overview

Azure managed disks are block-level storage volumes that are managed by Azure and used with Azure Virtual Machines.

I am unable to get a correlation between a Page Blob and whether Azure Managed Disk uses Page Blob ?
It looks like Unmanaged disk uses Page Blob, but does Managed Disk also use Page Blob for its VHD ?

Regards

Saket

Answer 1

anonymous userChiluveru-3827 Yes, Premium and Standard disks (managed and unmanaged) are backed by Page Blobs. We can try to provide a more specific answer if you could clarify the context behind the question.

Additional information:

While creating a VM by default we use the Managed disk.

Page blobs are for random read/write storage, such as VHD's (in fact, page blobs are what's used for Azure Virtual Machine disks). Max. size 8TB. Supported by both regular and Premium Storage.

Page Blobs: Optimized for random read and write operations. e. g. VHD

Collection of 512-byte pages optimized for random read and write operations and Page aligned random reads and writes IaaS Disks, Event Hub, Block level backup

You can export a page blob snapshot as a page blob and then create a Managed Disk from the exported page blob. Page blobs are used to hold random-access files up to 8 TB in size. Page blobs are used primarily as the backing storage for the VHDs used to provide durable disks for Azure Virtual Machines (Azure VMs). They have named page blobs because they provide random read/write access to 512-byte pages.

Page blobs are synonymous to Disks (Block Storage) which allows customers to migrate their Block Storage to Cloud. Object Storage is our scale-out storage offering that competes with S3.

About Page Blob:
Page blobs are a collection of 512-byte pages optimized for random read and write operations. To create a page blob, you initialize the page blob and specify the maximum size the page blob will grow. To add or update the contents of a page blob, you write a page or pages by specifying an offset and a range that align to 512-byte page boundaries. A write to a page blob can overwrite just one page, some pages, or up to 4 MiB of the page blob. Writes to page blobs happen in-place and are immediately committed to the blob. The maximum size for a page blob is 8 TiB.

Azure virtual machine disks are backed by page blobs. Azure offers two types of durable disk storage: premium and standard. Premium storage for page blobs is designed for Azure virtual machine workloads that require consistent high performance and low latency. For detailed information, see the Premium solid-state drives (SSD) section of the article Select a disk type for IaaS VMs. For information about the scalability targets for premium storage for page blobs, see Azure Storage Scalability and Performance Targets.

Hope this helps!

Kindly let us know if the above helps or you need further assistance on this issue.

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