10 - Storage

Definitions

• memory can be directly addressed from the CPU (load/store)
• storage need block-level data transfers to the memory

Hardware

• Tape, HDD, NAND / SSD, persistent memory, DRAM, CPU cache and CPU register
  • slower to faster
  • cheaper to expensive

Large Scale File Systems (BLOB)

• Distributed File Systems (ex. Google Drive): Large files on multiple nodes
• NoSQL
  • key-value store → MongoDB, Cassandra, Redis…
• NewSQL
  • Relational dbs scalable and fault-tolerant (Google Spanner, VoltDB)

GFS

• Google File Storage
  • files splitted into 64 or 128mb chunks
  • stored as plain files on chunk servers
  • no caching
  • fault tolerance: at least 3 replicas
  • load balancing: data distributed across servers
  • API: supports