Traditionally, there were three kinds of networked/centralized storage systems in an enterprise in addition to the directly attached storage that may have come with the servers:
- Storage Area Network (SAN) - block level storage
- Network Attached Storage (NAS) - file level storage (a.k.a Binary Large Object Storage)
- Tape storage - archive storage
Block storage is something that you can attach to a machine and then format and put a filesystem on, so a SAN can be considered akin to a local disk connected with a long network cable.
BLOB storage/file storage is a system where you can store files without bothering about the filesystem, block size, and so on.
While there are other differences between NAS and SAN (NAS ...