Disks and Storage

Part of the Linux course

"No space left on device." The service stops writing, the database refuses connections, and everything downstream falls over, all because some directory you have never heard of quietly grew. Storage is the failure that gives no warning until it gives you every warning at once.

Storage on Linux is a stack, and every confusing message makes sense once you can name which layer it came from. A physical disk is divided into partitions. Each partition is formatted with a filesystem. Each filesystem is attached somewhere in the single directory tree.