• NAS operating systems are optimized for file services: – Stripped-down versions of Unix or Windows, or – Purpose-built on Linux, BSD, etc microkernel
• Advantages over Traditional File Servers: – Better performance – Enhanced file security
– Cross-protocol locking enables support for heterogeneous environments
– Much better scalability
NAS operating systems need to be small in order to perform their specialized functions as fast as possible. Some NAS operating systems use stripped- down versions of existing operating systems like Unix or Windows, with performance enhancements for file services. Others use a specialized NAS operating system that is built on just the microkernel of an open-systems OS like Linux or BSD Unix.
NAS offers several advantages over standard Windows or Unix file servers: File I/O typically executes in kernel mode and avoids much of the context switching overhead that would be encountered if file I/O were taking place at the user process level, as on a standard file server. This translates to better overall performance. Another NAS performance advantage is that the processing load is split between the application host and the NAS appliance. Kernel-level file security is less prone to security breaches. Applications depend on the implementation of mandatory file locking. Standard file servers allow this in homogeneous environments, but