Cold storage is a computer system or mode of operation designed for the retention of inactive data.
Examples of data types for which cold storage may be suitable include information a business is required to keep for regulatory compliance, video, photographs, and data that is saved for backup, archival or disaster recovery purposes.
High-performance primary storage is generally considered too expensive for inactive data that is retained on a long-term or indefinite basis. Design priorities for cold storage may include low cost, high capacity and data durability. Data retrieval and response time can be significantly slower for a cold storage system than for devices or systems designed for active data. Common media choices include Linear Tape-Open (LTO) tape and commodity hard disk drives (HDDs).
Public cloud services targeting cold storage include Amazon Glacier, Google Cloud Storage Nearline and Microsoft Azure Cool Blob Storage. These services offer lower data availability at a lower price per gigabyte than alternative cloud storage offerings sold by Amazon, Google and Microsoft.
The Open Compute Project (OCP), driven by Facebook, includes initiatives dedicated to cold storage. The OCP storage committee focuses on the development of specifications and software intended to drive innovation in hardware and to facilitate greater efficiency and value. The OCP project to create high-capacity, low-cost cold storage identified shingled magnetic recording (SMR) HDDs with spin-down capability as a highly suitable and cost-effective technology for cold storage. Facebook has also tested Blu-ray discs and expressed interest in low-endurance flash for cold storage.
Facebook has built cold storage facilities as part of its data centers in Prineville, Oregon, and Forest City, North Carolina. Design priorities have included low power consumption, system efficiency, high density, scalability, data durability and future-proofing. Facebook has discussed its use of erasure coding for space-efficient data protection.