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July 26, 2020

Azure Managed Disks vs Unmanaged Disks


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 offering in case of storage disk’s i.e. managed and unmanaged disk. This article discusses the differences between Managed and Unmanaged disks.

In unmanaged disks, you must create storage account to hold the disks (VHD files) for your Virtual Machines.

With Managed Disks, 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 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.

Features

Managed Disks

Unmanaged 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.

ULTRA DISK CONFIGURATION 

UNIT

MONTHLY PRICE

  • Disk Capacity (GiB) 
  • Provisioned IOPS 
  • Provisioned Throughput (MB/s)
  • Provisioned vcpu reservation charge*
  • GiB  
  • IOPS
  • Mbps
  •  vCPU
  • $0.12
  • $0.05
  • $1.01
  • $4.38

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.

Disk Category

Disk Type and Size

Monthly Cost

Cost for 10,000 Data Transactions

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
(priced per hour)

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.



Azure Ultra

Azure Premium Disk

Standard SSD Disk 

Azure Standard HDD Disk


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
P6: 64 GiB
P10: 128 GiB
P15: 256 GiB
P20: 512 GiB
P30: 1024 GiB
P40: 2048 GiB
P50: 4095 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
E6: 64 GiB
E10: 128 GiB
E15: 256 GiB
E20: 512 GiB
E30: 1024 GiB
E40: 2048 GiB
E50: 4095 GiB

E60: 8,192 GiB

E70: 16,384 GiB

E80: 32,768 GiB

Unmanaged Disks: 1 GiB – 4 TiB (4095 GiB)

Managed Disks:
S4: 32 GiB
S6: 64 GiB
S10: 128 GiB
S15: 256 GiB
S20: 512 GiB
S30: 1024 GiB
S40: 2048 GiB
S50: 4095 GiB

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:

Storage Account Type

Supported Services

Supported Performance Tiers

Supported Access Tiers

Replication Options

Deployment Model

Encryption




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.

(Last Updated On: July 16, 2021)

Last Updated 2 weeks ago

About the Author

With a Master’s degree in Information System’s from Griffith University, Awais took up technology to explore his passion for cloud computing and IT security. He has a love for challenges and is fervent about his work.

Awais Khalid

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