Specifications
111
Figure 12.3a Network-attached storage
NAS provides a single storage device that is directly attached to a LAN and oers shared storage
to all clients on the network. A NAS device is simple to install and easy to administer, providing a
low-cost storage solution. However, it provides limited throughput for incoming data because it
has only one network connection, which can become problematic in high-performance systems.
SANs are high-speed, special-purpose networks for storage, typically connected to one or more
servers via ber. Users can access any of the storage devices on the SAN through the servers, and
the storage is scalable to hundreds of terabytes. Centralized storage reduces administration and
provides a high performance, exible storage system for use in multi-server environments. Fiber
Channel technology is commonly used to provide data transfers at four gigabits per second and
to allow large amounts of data to be stored with a high level of redundancy.
Figure 12.3b A SAN architecture where storage devices are tied together and the servers share the storage capacity.
Computer server with video
management software
Network switch,
broadband router or
corporate firewall
Axis network cameras
Separate
storage
Server Server Server Server
TCP/IP LAN
Fiber channel switch
RAID disk
array
Fiber channelFiber channel
RAID disk
array
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BANDWIDTH AND STORAGE CONSIDERATIONS - CHAPTER 12