What is block storage?

Block storage for flexible, fast access

Block storage is a form of cloud storage that is used to store data, often on storage area networks (SANs). Data is stored in blocks, with each block stored separately based on the efficiency needs of the SAN. Each block is assigned a unique address, which is then used by a management application controlled by the server's operating system to retrieve and compile data into files upon request. Block storage offers efficiency due to the way blocks can be distributed across multiple systems and even configured to work with different operating systems.

Block storage also offers an impressive level of flexibility because it can be accessed by different operating systems as mounted drive volumes and has the ability to use operating system–specific file systems (such as the New Technology File System (NTFS) for Windows and Virtual Machine File System (VMFS) for VMware). This makes using block storage quite similar to storing data on a hard drive within a server, except the data is stored in a remote location rather than on local hardware.

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How block storage works

A block is a fixed-size amount of memory within storage media that’s capable of storing a piece of data. The size of each block is determined by the management system. The block size is generally too small to fit an entire piece of data, and so the data for any particular file is broken up into numerous blocks for storage. Each block is given a unique identifier without any higher-level metadata; details such as data format, type, and ownership are not noted.

The operating system allocates and distributes blocks across the storage network to balance efficiency and functionality. When a file is requested, the management application uses addresses to identify the necessary blocks and then compiles them into the complete file for use.

By enabling storage across multiple environments, block storage separates data from the limitations of individual user environments. As a result, data can be retrieved through any number of paths to maximize efficiency, with high input/output operations per second (IOPS). The result is an approach that offers a higher level of efficiency than other cloud storage methods, making it ideal for high-performance applications or applications that require constant writing and retrieval.

Benefits of block storage

Block storage is a common and popular cloud storage choice because of its numerous benefits.

High efficiency: Block storage’s high IOPS and low latency make it ideal for applications that demand high performance.
Compatibility: Block storage works across different operating systems and file systems, making it compatible for enterprises whatever their configuration and environment.
Flexibility: With block storage, horizontal scaling is extremely flexible. Cluster nodes can be added as needed, allowing for greater overall storage capability.
Large file efficiency: For large files, such as archives and video files, data must be completely overwritten when using file or object storage. With block storage, the management application identifies only the block targeted for change within the large file, increasing the efficiency of data updates.

Limitations of block storage

Like any technology platform, block storage comes with limitations despite its numerous benefits.

Greater cost: While block storage is easily scalable, it can also be expensive due to the cost of SANs. In addition, managing block storage requires more-specialized training for management and maintenance, increasing the overall expense.
Performance limitations: With block storage, metadata is built in and hierarchical, and it is defined by the file system. Because data is broken up into blocks, searching for a complete file requires the proper identification of all its pieces. This can create performance issues for operations accessing the metadata, particularly with folders featuring a large number of files. While the tipping point is usually about 10,000 files, some issues are seen with directories containing only 1,000 files.

Block storage use cases

As with object storage and other types of cloud storage, block storage works best in specific circumstances based on user needs and given parameters. The following are just several of many effective block storage use cases:

Containers: Block storage supports the use of container platforms such as Kubernetes, creating a block volume that enables persistent storage for the entire container. This allows for the clean management and migration of containers as needed.
Email servers: Email servers can take advantage of block storage’s flexibility and scalability. In fact, in the case of Microsoft Exchange, block storage is required due to the lack of support for network-attached storage.
Databases: Block storage is fast, efficient, flexible, and scalable, with support for redundant volumes. This allows it to support databases, particularly those that handle a heavy volume of queries and where latency must be minimized.
Disaster recovery: Block storage can be a redundant backup solution for nearline storage and quick restoration, with data swiftly moved from backup to production through easy access.

Why block storage?

Block storage continues to be an efficient and flexible cloud storage option for enterprises require high-performance workloads or need to manage large files. Learn more about how Oracle delivers block storage solutions with Oracle Cloud Infrastructure.