Why Centralised Storage Refuses To Go Away
ArchitectingIT, Monday, May 27th, 2024
It is over 30 years since EMC introduced the first Integrated Cache Disk Array to the enterprise data centre market, signalling the transition to centralised or SAN storage. Despite the best efforts of hyper-convergence, the demand for centralised storage remains strong. Even as the public cloud gains significant traction, SAN storage refuses to go away.
In 1990, EMC Corporation (acquired by Dell in 2015/2016) introduced the first ICDA or Integrated Cache Disk Array. The system differed from the storage that had been deployed up to that point as it included software and memory-protected DRAM to abstract and optimise the reading of I/O to and from (relatively) cheap media.
Only three years earlier, the seminal work by Patterson, Katz and Gibson had standardised definitions for RAID, or Redundant Array of Inexpensive Disks (now Independent Disks). Although the first Symmetrix systems from EMC only supported RAID-1 mirroring, the use of system memory as a cache allowed features such as snapshots and replication to be introduced into future models. RAID was expanded to include more efficient RAID-5 and, of course, eventually, RAID-6 for greater protection against large-disk failures.