What is block storage? All you need to know
Block storage is a storage technology in which data is divided into equally sized blocks and stored independently. These blocks can be directly addressed via addresses, enabling particularly fast access times and high performance. This makes the architecture ideal for databases or virtual machines.
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What is block storage?
While with file storage, entire files are stored in a folder system, data in block storage—unlike object storage—is stored in the form of blocks. These blocks are stored where the system deems most appropriate. It divides files evenly into blocks, causing the files to lose their original significance and making them unable to be easily executed or opened. Blocks are units of equal size. To ensure individual blocks can be found again, each block is assigned an address. When the server receives a request, it can then locate, reassemble, and deliver the data.
How does block storage work?
Block storage is commonly used within a Storage Area Network (SAN). In this setup, multiple servers can access data over a network, with software managing the precise location of each data block. Originally, block storage in SAN environments resembled a LAN, using components like switches and hubs. Today, however, block storage can also be deployed in cloud environments — a model often called block-level storage. Here, a traditional system of hard drives is virtually replicated.
Communication in a SAN usually happens via Fibre Channel (FC) or Internet Small Computer System Interface (iSCSI). FC is an interface designed for very high-speed transmissions. In contrast, the iSCSI method uses TCP and Ethernet, making it easy to integrate into existing networks.
Modern cloud providers use block storage as a flexible foundation for virtual machines or persistent container-volumes. The storage blocks are often managed via cloud-based administration APIs, enabling dynamic and automated provisioning in DevOps and Kubernetes-environments.
Advantages and disadvantages of block storage
Compared to other forms of data storage, block storage is considered particularly fast and highly redundant. Each block has an individual address through which the data can be accessed. Other storage methods rely on metadata, sometimes in very large quantities. The absence of this additional information can be both an advantage and a disadvantage. While the blocks remain very lean and can be directly accessed, if you want to deliberately store metadata, an additional database is necessary. The biggest disadvantage of block storage is the cost, as SANs rely on expensive hardware.
| Advantages | Disadvantages |
|---|---|
| High Speed | High Cost |
| Low Latency | No Metadata |
| Redundancy |
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Applications of block storage
Block storage showcases its advantages, especially in databases. The reason lies in the high speed with which data can be both read and written. Transactional databases need constant adjustments. Block storage delivers excellent results here, whereas other storage methods often involve delays. This is not ideal for business applications. Block-level storage is also used in virtual machines. The technology makes it easy to provide storage for virtualization.
Moreover, block storage also plays an increasing role in containerized applications. Persistent volumes can be efficiently provisioned through block-based storage solutions and are ideally suited for stateful workloads like databases or search indexes.