Block Storage

Block storage presents raw storage volumes — fixed-size blocks — to a compute instance, behaving like a virtual disk that you partition and format. Volumes persist independently of instances, can be detached and re-attached, and are the standard home for boot disks and databases.

Performance is specified in IOPS and throughput, and most providers let you provision these independently of capacity. Volume types range from general-purpose SSDs through provisioned-IOPS disks to cheap spinning or cold tiers for infrequently accessed data.

Unlike object storage, block storage is confined to a zone or region, and replication is your job unless you use a snapshot service. Budget for snapshots (usually incremental and billed per stored gigabyte) and test restores — a snapshot you have never restored is a hypothesis, not a backup.