General Overview to Azure Storage / Premium Storage for IaaS (Virtual Machines)


Primarily, you need to aware that information I will provide below presents current Azure Storage structure. Before Feb 2015, there was only standard storage structure that supports IaaS and PaaS. This standard structure comprises of four different storage types, Blob, Table, Queue, and File. Secondary, since February, Premium Azure storage is also available. This storage much faster than any other standard storage. However, Premium storage is only available in some regions and few type of IaaS servers.

Standard storage account gives you access to Blob storage, Table storage, Queue storage, and File storage

Blob storage stores file data. A blob storage can be any type of binary data, a document, VHD, media, or picture etc…

Blob storage offers two types of blobs. First type of blob storage is block blob. Block blob is designed for streaming and storing cloud objects and it is best for keeping backup files, or hosting pictures, media files. Max size of a block blob can be 200GB. Second type of blob storage is page blob. It is optimized for representing IaaS disks. It can be up to 1TB in size. An Azure VM network attached disk is a VHD stored as a page blob.

Premium Azure Storage

Azure platform offers two types of storage: Standard and Premium storage. Standard storage above stores data on HDD whereas Premium storage stores data on SSD. Premium storage is much faster and provides high performance and low latency. It can be up to 32 TB and 50.000 IOPS (Input/output operations per second) for read operation.

That storage requires Azure Premium storage account before creating a storage. Also it is available only few regions right now, West US, East US 2 and West Europe

Moreover, Premium storage supports only page blobs which are used to hold persistent disk for Azure Virtual Machines (IaaS). Premium storage account is locally redundant (LRS).

As it is mentioned above that only few type of VMs can access to Premium storage. These are DS series VMs. Choosing correct type of Premium storage and deciding correct DS server type in order to get perfect result are important before going further.

When a Premium disk is provisioned to a VM, how much IOPS and throughput can it get? That depends on the size of the disk. Today there are three types of Premium storage disks. P10, P20 and P30

Premium Storage Disk Type P10 P20 P30
Disk size 128 GB 512 GB 1024 GB (1 TB)
IOPS per disk 500 2300 5000
Throughput per disk 100 MB per second * 150 MB per second * 200 MB per second *


In order to get good result, make sure that there is sufficient bandwidth available on your VM. Let’s check DS series VMs to understand how much bandwidth can we get?

VM Size CPU cores Max. IOPS Max. Disk Bandwidth
STANDARD_DS1 1 3,200 32 MB per second
STANDARD_DS2 2 6,400 64 MB per second
STANDARD_DS3 4 12,800 128 MB per second
STANDARD_DS4 8 25,600 256 MB per second
STANDARD_DS11 2 6,400 64 MB per second
STANDARD_DS12 4 12,800 128 MB per second
STANDARD_DS13 8 25,600 256 MB per second
STANDARD_DS14 16 50,000 512 MB per second


If P10 storage is allocated to DS1 server which Max Disk bandwidth is 32MB per second, P10 disk can go up to 32GB per second not up to 100MB.

Storage Redundancy

There are three types of redundancy available in Azure. Business must decide what kind of storage they need before creating a storage in Azure.
Standard storage offers all those three types below whereas Premium offers only LRS.

LRS – Locally-Redundant Storage that maintains three copies of your data. LRS is replicated three times within a single facility in a single region. LRS protects your data from normal hardware failures, but not from the failure of a single facility.

ZRS – Zone-Redundant Storage that maintains three copies of your data. ZRS is replicated three times across two to three facilities, either within a single region or across two regions, providing higher durability than LRS. ZRS ensures that your data is durable within a single region.

GRS – Geo-redundant Storage is enabled for your storage account by default when you create it. GRS maintains six copies of your data. With GRS, your data is replicated three times within the primary region, and is also replicated three times in a secondary region hundreds of miles away from the primary region, providing the highest level of durability.

Note***: Once ZRS is created there is no convert option to any other type of replication.



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