What is blockstorage?

Block storage is a way of storing data where the storage medium is divided into fixed-size chunks called “blocks.” Each block acts like an individual hard drive that can be written to or read from independently. The system that uses the storage doesn’t see a single big file; it sees a collection of these blocks that can be arranged in any order the software needs.

Let's break it down

  • Block: A small, uniform piece of storage (often 512 bytes or 4 KB).
  • Device: Physical hardware like a hard‑disk drive (HDD), solid‑state drive (SSD), or a virtual disk in the cloud.
  • Controller: Software or firmware that maps logical block addresses (LBAs) to the actual physical locations on the device.
  • File system: The layer (e.g., NTFS, ext4) that organizes blocks into files and directories for the operating system.
  • Volume: A logical grouping of blocks presented to a server or VM as a single disk.

Why does it matter?

Block storage gives you fast, random access to data, which is essential for applications that need to read or write small pieces of information quickly. Because each block can be addressed directly, you can scale storage up or down, move blocks between devices, and create snapshots or clones without copying whole files. This flexibility makes it a backbone for high‑performance computing, databases, and virtual machines.

Where is it used?

  • Databases (SQL, NoSQL) that require low‑latency reads/writes.
  • Virtual machines and containers that need a virtual hard disk.
  • Enterprise applications like ERP or CRM systems.
  • Cloud services (AWS EBS, Azure Managed Disks, Google Persistent Disks).
  • Backup and disaster‑recovery solutions that snapshot block volumes.

Good things about it

  • High performance: low latency and high IOPS (input/output operations per second).
  • Random read/write capability, ideal for transactional workloads.
  • Easy to resize, snapshot, and clone.
  • Works with any operating system that supports a block device.
  • Can be provisioned on fast media like SSDs for even better speed.

Not-so-good things

  • More complex to manage than simple file storage; you need a file system on top of the blocks.
  • Typically more expensive per gigabyte, especially on high‑performance SSDs.
  • Not optimal for storing large, unstructured objects (e.g., media files) where object storage shines.
  • Requires careful planning of block size and alignment to avoid performance penalties.