NAS (Network Attached Storage) is storage that is shared over the ordinary network as files, using protocols like NFS or SMB. A NAS appliance is, in effect, a box of disks with a file server built in: recording servers mount it as a network drive and write video to it. It is simple to deploy, easy to expand, and a common choice for the warm and archive tiers of a surveillance system, or for smaller deployments where one shared store is enough.
Its appeal is simplicity and shareability. Because it presents files over standard network protocols, many servers and users can reach the same store without special hardware, and capacity grows by adding or swapping disks. For backup, archival, and moderate recording loads it is cost-effective and well understood, and surveillance-rated NAS units add features like larger write caches and surveillance-tuned disks.
The pitfall is throughput under continuous write. Surveillance is relentless sequential writing from many cameras at once, and file-level access over a shared network can become the bottleneck for heavy live recording — latency and protocol overhead cap how much sustained stream a NAS absorbs, well below what a block-level SAN manages. A NAS shared with other office traffic is worse still. Use NAS for archive, backup, and smaller or lighter-bitrate recording loads; for high-density live recording, put it on a dedicated storage network or move to SAN-class block storage, and always size for sustained write, not just capacity.
