San Versus Network Attached Storage (Nas) - IBM TotalStorage DS300 Best Practices Manual

Client
xSeries
Figure 1-1 A Storage Area Network
SANs create new methods of attaching storage to servers. These new methods
can enable great improvements in both availability and performance. Today's
SANs are used to connect shared storage arrays and tape libraries to multiple
servers, and are used by clustered servers for failover. They can interconnect
mainframe disk or tape to mainframe servers where the SAN devices allow the
intermixing of open systems (such as Windows, AIX) and mainframe traffic.

1.3 SAN versus Network Attached Storage (NAS)

Network Attached Storage (NAS) is basically a LAN-attached file server that
serves files using a network protocol such as Network File System (NFS). NAS is
a term used to refer to storage elements that connect to a network and provide
file access services to computer systems. An NAS storage element consists of
an engine that implements the file services (using access protocols such as NFS
or Common Internet File System (CIFS), and one or more devices, on which data
is stored. NAS elements may be attached to any type of network. From a SAN
perspective, a SAN-attached NAS engine is treated just like any other server.
Figure 1-2 on page 7 illustrates the difference between a SAN and NAS.
6
IBM TotalStorage DS300 and DS400 Best Practices Guide
Client Client
Network & LANS
pSeries iSeries
Storage Area Network
Storage Area Network
DS
DISK DISK
400
Client Client
UNIX
Tape
Tape
Library
Client Client
zSeries