distributed-storage

# Distributed Storage Distributed storage is where durability, consistency, latency, and cost collide. Every design choice trades among them, and the trade-offs cannot be hidden from applications for long. This skill covers the landmark systems and the recurring patterns they embody, from the GFS master-chunkserver split that defined cloud-scale storage, to the Dynamo-style consistent-hash rings that power modern object stores, to the Spanner-style externally consistent databases built on TrueTime. **Agent affinity:** ghemawat (GFS and storage systems craftsmanship), dean (BigTable, Spanner, and the evolution from GFS), decandia (Dynamo and eventually consistent stores) **Concept IDs:** cloud-cinder-block-storage, cloud-swift-glance-object-image, cloud-nova-instances ## The Three Storage Shapes Cloud platforms expose storage in three shapes, each with a different access model and consistency profile. **Object storage.** Immutable blobs with rich metadata, accessed by key, usually over HTTP. Examples: Amazon S3, OpenStack Swift, Google Cloud Storage. Consistent hashing distributes objects across nodes; replication or erasure coding provides durability. Objects are typically append-or-replace — partial updates are not the native operation. Best for: media, backups, logs, analytics input, static web content. **Block storage.** Virtual disks presented as block devices to virtual machines. Examples: Amazon EBS, OpenStack Cinder, Google Persistent Disk. Provides the POSIX-is...