Azure Disk Storage overview
When migrating your data center from on-premises to the cloud, you have a lot of disk storage options available. It is very common to get confused in a lot of options. In this article, we'll be covering most of the common azure storage options available.
Difference Between Managed Disks and Unmanaged Disks
Microsoft has two offerings in the case of storage disk’s i.e. managed and unmanaged disk. This article on disks will discuss the differences between Managed and Unmanaged disks
In Unmanaged Disk storage, you must create a storage account in resources to hold the disks (VHD files) for your Virtual Machines.
With Managed Disk Storage, you are no longer limited by the storage account limits. You can have one storage account per region.
Benefits of Using Managed Azure Disk Storage
The managed disk provides less access time, enhanced manageability and high availability which provides the following features.
- Simple - Abstracts underlying storage account/blob associated with the Virtual Machine disks from customers. Eliminates the need to manage storage account for IaaS Virtual Machines (VMs)
- Secure by default – Role based access control, storage encryption by default and encryption using own keys
- Storage account limits do not apply – No throttling due to storage account IOPS limits
- Big scale -20,000 disks per region per subscription.
- Better Storage Resiliency - Prevents single points of failure due to storage Supports both Standard and Premium Storage disks.
Management | Is an ARM (Azure Resource Manager) object (resource) | Is not an ARM resource, but a file (.vhd) residing on an Azure Storage Account. The latter is an ARM object |
Size | The managed disks sizes are fixed (and can be resized). Which means that you cannot choose a custom size. You will need to pick up from a list. | You can choose the disk size during the provisioning (and can be resized) when using Standard Storage. |
Performance | A managed disk has a predictable performance, with standard HDD (Upto 2000 IOPS), with Standard SSD storage (Upto 6000 IOPS), Premium SSD storage (Upto 20000 IOPS), Ultra Disk offering (Upto 160,000 IOPS) *IOPS depends on the size of the disk. | Only premium storage disks have a predictable performance (depends on the disk). Standard storage has a predictable performance (500 IOPS) unless they are impacted by the Storage Account performance limits (A maximum of 40 disks per standard storage account is recommended, otherwise disks can be throttled). |
Availability | When placing Azure Virtual Machines using managed disks under an Availability Set, disks are placed on different fault domains in order to achieve the better SLA (The Availability Set SLA is only for compute) | When placing Azure Virtual Machines using unmanaged disks under an Availability Set, there is no guarantee that the disks are placed on different fault domains, even if they are on different Storage Accounts. |
Redundancy | LRS | LRS, GRS |
Encryption | ADE, SSE (Coming soon) | ADE, SSE |
Are managed disks more expensive than unmanaged disks ?
The managed disk is expensive as compared to unmanaged disks.
Azure Disk Types
Azure is offering different types of storage disk’s, below we will discuss all the disk types their workload examples and starting prices of each type.
Note: Unmanaged storage is only available in HDD. SSD and Ultra-Disk only offers Managed storage.
Azure Standard HDD
These disks are designed for low priority workloads. Standard HDD is based on magnetic drives. Standard HDD is the cheapest solution.
Example workloads for Standard HDD
- Development
- Testing
- Backups
- Disaster Recovery
Storage Price of Standard HDD
$0.048125 / GB per month
Azure Standard SSD
Standard SSD is designed for light to moderate use. Microsoft provide 99% capacity and performance thresholds but not guaranteed.
Example workloads for Standard SSD
- Web servers
- Application server
- Enterprise application
Storage Price of Standard SSD
$0.075 / GB per month
Azure Premium SSD
Premium SSD’s is designed for performance sensitive and for production environment. Only used with compatible VMs. Unlike standard SSD you will get reserved performance and capacity.
Example workloads for Premium SSD
- Dynamics CRM
- SQL Server
- MongoDB
- Cassandra
Storage Price of Premium SSD
$0.15 / GB per month
Azure Ultra-Disk
Ultra-Disk provide high throughput, high IOPs and low latency. Ultra-disk provides configurable capacity and performance features.
Example workloads for Ultra-Disk
- SAP HANA
- High throughput databases
Storage Price of Ultra-Disk
Price depends on disk configuration. Configuring Disk for Ultra-Disk depends on 4 Units.
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Unmanaged Storage
You may only get unmanaged storage in HDD. With the unmanaged HDD, you need to create a storage account and need to specify the storage account while creating he disk.
Example workloads for Unmanaged storage
- Testing
- Code repository
Storage Price of Unmanaged storage
$0.02 per GB per month
Common types and Data Transactions pricing
Below table illustrate the monthly pricing of common types on managed disks.
Premium SSD | P10, 128 GB | $17.92 | N/A |
P30, 1TB | $122.88 | N/A | |
P70, 16TB | $1,638.40 | N/A | |
Standard SSD | E10, 128GB | $9.60 | $0.002 |
E30, 1TB | $76.80 | $0.002 | |
E70, 16TB | $1,228.80 | $0.002 | |
Standard HHD | S10, 128GB | $5.89 | $0.0005 |
S30, 1TB | $40.96 | $0.0005 | |
S70, 16TB | $524.29 | $0.0005 | |
Ultra-Disk | 512 GB | $118.08 | Per-hour, per-GB charges for provisioned IOPS and throughput |
Azure Disks Comparison
The following table provides a comparison of Standard HDD, Standard SSD, and Premium SSD for unmanaged and managed disks to help you decide what to use, along with available disk sizes in different options.
Disk Type | Solid State Drives (SSD) | Solid State Drives (SSD) | Solid State Drives (SSD) | Hard Disk Drives (HDD) |
Overview | Next generation high-performance Solid-State Drive (SSD) configurable peformance attributes that provide the lowest latency and consistent high IOPS/throughput. | SSD-based high-performance, low-latency disk support for VMs running IO-intensive workloads or hosting mission critical production environment. | More consistent performance and reliability than HDD. Optimized for low-IOPS workloads. | HDD-based cost-effective disk for infrequent access. |
Scenario | Production and performance sensitive workloads | Production and performance sensitive workloads | Web servers, lightly used enterprise applications and Dev/Test | Backup, Non-critical, Infrequent access |
Disk Size | Ultra-Disk: 4 GiB Ultra-Disk: 8 GiB Ultra-Disk: 16 GiB Ultra-Disk: 32 GiB Ultra-Disk: 64 GiB Ultra-Disk: 128 GiB Ultra-Disk: 256 GiB Ultra-Disk: 512 GiB Ultra-Disk: 1,024-65,536 (In increments of 1TiB) | Managed Disks only: P1: 4 GiB P2: 8 GiB P3: 16 GiB P4: 32 GiB P60: 8,192 GiB P70: 16,384 GiB P80: 32,768 GiB | Managed Disks only: E1: 4 GiB E2: 8 GiB E3: 16 GiB E4: 32 GiB E60: 8,192 GiB E70: 16,384 GiB E80: 32,768 GiB | Unmanaged Disks: 1 GiB – 4 TiB (4095 GiB) Managed Disks: S60: 8,192 GiB S70: 16384 GiB S80: 32,768 GiB |
Max Throughput per Disk | Upto 2000 MiB/s | Upto 900 MiB/s | Upto 750 MiB/s | Upto 500 MiB/s |
Max IOPS per Disk | Upto 160,000 IOPS | 20,000 IOPS | Upto 6000 IOPS | Upto 2000 IOPS |
Here's the reference article.
Disk Caching in Azure
A disk cache is a cache memory that is used to speed up the process of storing and accessing data from the hard disk. In Azure we have Premium Disks for Caching. Microsoft recommends enabling caching for faster processing of frequently used data.
Note: There is no additional price for caching.
Storage Tiers in Azure
There are three types of storage tiers, so that you can store your data in most cost-effective manner and depending on how you use it.
Hot Access Tier
Hot Access Tier is the one where the frequently used data resides. It has high storage costs and low access costs. For critical frequently used applications like SQL, Microsoft always recommends using Standard/Premium SSD as SSD already has Caching in it.
Cool Access Tier
Cool Access Tier is the one where infrequently accessed data resides and stored for at least 30 day. It has lower storage costs and higher access costs compared to hot storage.
Archive Access Tier
Archive Access Tier is used for storing data that is rarely accessed and stored for at least 180 days with flexible latency requirements. The archive backup storage tier is only available at the blob level and not at the storage account level.
Types of Storage Accounts
General Purpose v2
General-purpose v2 storage account support the latest Storage features and incorporate all of the functionality of general-purpose v1 and Blob storage account. General-purpose v2 account deliver the lowest per-gigabyte capacity prices for Storage, as well as industry-competitive transaction prices. General-purpose v2 storage account support these Storage services:
- Blobs (all types: Block, Append, Page)
- Data Lake Gen2
- Files
- Disks
- Queues
- Tables
General purpose v1
General-purpose v1 storage account provide access to all Storage services, but may not have the latest features or the lowest per gigabyte pricing. General-purpose v1 storage account support these Storage services:
- Blobs (all types)
- Files
- Disks
- Queues
- Tables
You should use general-purpose v2 account in most cases. You can use general-purpose v1 account for these scenarios:
Your applications require the classic deployment model. General-purpose v2 account and Blob storage account support only the Resource Manager deployment model.
Your applications are transaction-intensive or use significant geo-replication bandwidth, but don't require large capacity. In this case, general-purpose v1 may be the most economical choice.
You use a version of the Storage Services REST API that is earlier than 2014-02-14 or a client library with a version lower than 4.x. You can't upgrade your application.
Block blob storage
A BlockBlobStorage account is a specialized storage account in the premium performance tier for storing unstructured object data as block blobs or append blobs. Compared with general-purpose v2 and BlobStorage account, BlockBlobStorage account provide low, consistent latency and higher transaction rates.
BlockBlobStorage account don't currently support tiering to hot, cool, or archive access tiers. This type of storage account does not support page blobs, tables, or queues.
File storage
A FileStorage account is a specialized storage account used to store and create premium file shares. This storage account kind supports files but not block blobs, append blobs, page blobs, tables, or queues.
FileStorage account offer unique performance dedicated characteristics such as IOPS bursting.
Blob storage
Blob Storage helps you create data lakes for your analytics needs and provides storage to build powerful cloud-native and mobile apps. Optimize costs with tiered storage for your long-term data, and flexibly scale up for high-performance computing and machine learning workloads.
Storage Accounts and Capabilities
The following table describes the types of storage account and their capabilities:
General-purpose V2 | Blob, File, Queue, Table, Disk, and Data Lake Gen2 | Standard, Premium | Hot, Cool, Archive | LRS, GRS, RA-GRS, ZRS, GZRS (preview), RA-GZRS (preview) | Resource Manager | Encrypted |
General-purpose V1 | Blob, File, Queue, Table, and Disk | Standard, Premium | N/A | LRS, GRS, RA-GRS | Resource Manager, Classic | Encrypted |
BlockBlobStorage | Blob (block blobs and append blobs only) | Premium | N/A | LRS, ZRS | Resource Manager | Encrypted |
FileStorage | File only | Premium | N/A | LRS, ZRS | Resource Manager | Encrypted |
BlobStorage | Blob (block blobs and append blobs only) | Standard | Hot, Cool, Archive | LRS, GRS, RA-GRS | Resource Manager | Encrypted |
Conversion from HDD to SSD
Please follow the link to get details about how to convert from HDD to SSD.