Demystifying Azure Storage – Understanding Blobs, Queues, Tables, and Files

The Azure Storage platform includes the following data services:

• Table – A NoSQL store for schema-less storage of structured data.
• Blob – A massively scalable object store for text and binary data.
• Queue – An asynchronous message queueing between application components.
• Files – Managed file shares for cloud or on-premises deployments.

Azure Table Storage

Azure Table Storage is a scalable, NoSQL, key-value data storage system that can be used to store large amounts of data in the cloud. This storage offering has a schema-less design, and each table has rows that are composed of key-value pairs. You can use Table storage to store and query huge sets of structured, non-relational data, and your tables will scale as demand increases.

Azure Blob Storage

Blob Storage is Microsoft Azure’s service for storing binary large objects or blobs which are typically composed of unstructured data such as text, images, and videos, along with their metadata. Blobs are stored in directory-like structures called “containers.”

Binary Large Object is the storage arena for text, audio, images, and video. Every blob resides inside a container. Blob storage acts as the persistent store, where the data is stored for a long time. Three options include Private, Public Container, and Public Blob.

A container organizes a set of blobs, similar to a directory in a file system. A storage account can include an unlimited number of containers, and a container can store an unlimited number of blobs. The container name must be lowercase.

Blob Storage Categories

Although blob allows for the storage of large binary objects in Azure, these are optimized for three different storage scenarios:

• Block blobs: These are blobs that are intended to store discrete objects such as images, log files, and more.  In this storage option, individual blocks with unique IDs are created. It is mainly used for uploading big-size data.
• Page blobs: These are optimized for random read and write operations and can grow up to 8TB in size. Within the page blob category, Azure offers two types of storage: standard and premium. The latter is the most ideal for virtual machine (VM) storage disks (including the operating system disk).  Data from the virtual machines are stored as virtual documents and files on the page blob. For the virtual machine, it acts as a disk.
• Append Blobs: Append blobs are used to append data. This means that each time you make changes to the blob, the data will be appended at the end of the blob. Data cannot be changed or deleted, only appended. The Append Blob is specifically customized to increase efficiency. It can also help in logging the data directly from the VMs.

Azure Blob Access Tiers

To begin with, Azure storage provides various access tiers. Further, these allow you to store blob object data in the most cost-effective method. Furthermore, the available access tiers involve the following:

• Hot access tier – The hot access tier offers higher storage costs than the other two- cool and archive tiers. Also, they are at the lowest access costs.
• Cool access tier – The cool access tier comes with lower storage costs and higher access costs in comparison to hot storage. Not to mention, this tier is designed for data that will remain in the cool tier for a minimum of 30 days.
• Archive Access tier – The Archive access tier offers the lowest storage cost. However, it has higher data retrieval costs compared to the hot and cool tiers. Not to mention, data must remain in the archive tier for at least 180 days or be subject to an early deletion charge. While a blob is in archive storage, the blob data is offline and can’t be read, overwritten, or modified. To read or download a blob in the archive, you should first rehydrate it to an online tier.

The Storage or the blob files as Hot means we want these files readily accessible. The Data stored in these types of storage are always readily available.

Once the Access Tier is moved to the Archive tier, your Blob will be inaccessible. Archive storage is offline. At this time if you want to access the blob you will get a “This operation is not permitted on an archived blob” error. To access your archive data, you need to rehydrate back your storage tier to either Hot or Cool. This process is called Blob Rehydration. The rehydration process may take several hrs. ( up to 15 hrs. to complete).

When the rehydration is in progress, the blob will be still inaccessible.  You can start the rehydration process by just updating the tier for the blobs, and checking the status of the rehydration. Once the rehydration is complete, you can start accessing the data.  This type of access tier is ideal for Long-term backup, and archival datasets where frequent data access is not required. The archive tier has the lowest storage cost and highest access cost.

Azure Queue Storage

Queues have been around for a long time — their simple FIFO (first in, first out) architecture makes queues a versatile solution for storing messages that do not need to be in a certain order. In simple terms, Azure Queue Storage is a service that allows users to store high volumes of messages, process them asynchronously, and consume them when needed while keeping costs down by leveraging a pay-per-use pricing model.

Azure File Storage

Azure file storage makes it easy to move applications that depend on regular file shares to the cloud. Microsoft Azure File Service is is a cloud storage service that allows Windows Server administrators to access Server-Message-Block-Protocol (SMB) shares in the Azure cloud by setting up file shares in the Azure management console. Azure File Service can be a shared resource so test machines and development have access to one file share when installing tools, applications, and utilities.