Microsoft Azure: Blob/Object Storage Account Overview

Microsoft Azure offers a variety of storage services for business and developers, but requires some time to understand its basics. Four storage types, three storage classes within an object storage, two account types and two access tiers — pretty complicated, huh? But this complexity shouldn’t drive you away from using cost-effective and reliable storage.

In this blog post we uncover MS Azure architecture and explain major differences between storage types, classes, access tiers and pricing.

Microsoft Azure Cloud Storage Architecture

Basically, Microsoft Azure has four major storage types:

• Object/Blob Storage used for storing unstructured data
• Table Storage — Microsoft NoSQL/attribute store
• Queue Storage provides communication between application components
• File Storage for file sharing between team members

Users can choose between two different account types to access their data in the storage:

• General-Purpose Account that gives an access to Object, Table, Queue, File storage services and VM disks.
• Blob Storage Account — designed to work with Block and Append Blob Storage services only in the Object/Blob Storage environment

Summarizing points below, we could say that the Blob/Object Storage is the one and only suitable. So, let’s get deeper in understanding three storage classes within an Object Storage:

• Block Blob
• Append Blob
• Page Blob

But first, look at the scheme that illustrates the Microsoft Azure architecture, we’ve explained above, to understand storage services hierarchy.

Block Blobs

The BLOB in this article stands for “Binary Large OBjects”.

Block Blobs are designed for massive amounts of unstructured data such as backups, documents or images. Put it simple, blobs are containers, where your data will be stored. When you upload your files they break up into a multitude of 4MB chunks called blocks. Each blob can contain 50.000 blocks. So the total capacity of a blob is more or less 195 GB (4MB * 50,000). Blocks acquire unique IDs in the system, so they can be deleted from the file or replaced by other blocks (the whole endpoint file will be slightly edited) and also copied with new ID.

The catch is you have to commit new blocks — merge them with the blob, or all unassociated blocks would be deleted in a week. Good news blocks upload in parallel saving time and can be uploaded in any order, which helps provide stable backup in zones with poor Internet connection. The user can set the order of blocks in the blob manually after the upload is done, which allows to quickly determine failed or unnecessary blocks and re-upload them.

Append Blobs

Append Blobs are pretty much the same as Block Blobs: they also consist of blocks and have the same limitations, but were designed mainly for append operations. On the contrary with a Block Blob, where new blocks can replace the existing blocks no matter the location, in Append Blobs blocks are written to the end of the blob only. This means a user can’t update or delete existing blocks, but only merge different sequences under one Blob. Therefore unlike Block Blob storage, Append Blobs don’t use block IDs.

Page Blobs (Disks)

Page Blobs represent a different concept within Microsoft Azure. Unlike Block and Appended Blobs they consist of 512-byte pages optimized for both read and write operations. Page blobs are used with MS Azure virtual machines. To upload data into the Page Blob a user has to write pages and specify an offset within 512-byte range.

There are two types of Page Blob storage:

• Standard — for VMs with an average amount of write/read operations
• Premium — for high amount of write/read operations and decreased latency

Cold Blob vs Hot Blob

There are also two access tiers available for users divided by two different types of data.

Hot Blob — for data that require frequent access, i.e. user data or recent backups. The pricing of storing the data is higher than the Cool tier, but the cost of access requests is much lower.

Cool Blob — for data that doesn’t require frequent access: old backup versions, archives and so on. Here you pay less for storing such data, but the cost of access request is higher.

Note: Hot and Cool access tiers are currently available in Central US, East US 2, North Central US, North Europe, West Europe, Southeast Asia, Japan East and Japan West regions.

Look at the comparison table to summarize the results.

Unfortunately, the understanding of storage classes is not the only thing that affects data security and availability. Now it’s time to shed some light on how Microsoft Azure protects your data and how much it costs.

Redundancy Levels

Microsoft Azure offers 4 data redundancy options:

• Locally Redundant Storage (LRS) — a few copies of your data inside one data center. On practice it means the lowest level of disaster protection, since data center can be knocked out by power outage or a region-level natural disaster
• Zone Redundant Storage (ZRS) — three copies of your data set spread within one region or across regions. Works only for Block Blob
• Geographically Redundant Storage (GRS) — three copies within one region plus another three copies in a distant region
• Read-Access Geographically Redundant Storage (RA-GRS) — the same as GRS option, but also allows to have the read access to the data in the distant data center

To put it simple, we’ve also compared all replication levels in one table:

Pricing

Now it’s time to see how Blob Storage account stacks with replication levels, hot/cold access tiers and pricing across MS Azure regions. Let’s first compare the storage price for one GB and total storage capacity lower than 1 TB for regions that are currently support Cool and Hot access options*:

Now, let’s compare the price for one GB of storage (total capacity lower than 1 TB) for regions that don’t support Cool access tier yet*:

*Prices are valid on 6/22/2016

Compare your budget with storage costs and decide what region and replication level to use for backup needs.

Which Class is Better

In this article we have overviewed the major storage types within Microsoft Azure Blob Storage and storage classes in Block/Object Storage: Block Blobs, Append Blobs and Page Blobs. Here’s the summary:

• Block Blobs are the best fit for backups, but need to be handled with care (committed)
• Append Blobs are similar to Block Blobs in nature, but allow only append actions with blocks and block blobs. You can’t replace blocks or change the block order on uploading
• Page Blobs are storage drives that work with Microsoft Azure virtual machines, so have two Performance tiers for different workloads.

In the next material we will uncover more details about MS Azure Cloud Storage options. Don’t hesitate to ask your questions and share thoughts in the comment section.

See also:

• Amazon S3, Microsoft Azure and Google Cloud Storage Pricing Comparison
• How to Restore to Azure VM With CloudBerry Backup
• How to Sign up to Azure VM
• CloudBerry Lab Supports New Microsoft Azure Cool Blob Storage