Axis IP-Surveillance system Design Manual page 46

8.4. Storage considerations
When the amount of stored data and management requirements exceed the limitations of a direct at-
tached storage, a network-attached storage (NAS) or storage area network (SAN) allows for increased
storage space, flexibility and recoverability.
Axis network cameras
Figure 8.4.a. Network-attached storage
NAS provides a single storage device that is directly attached to a LAN and offers 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 fiber. 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 perfor-
mance, flexible storage system for use in multi-server environments. In a SAN system, files can be stored
block by block on multiple hard disks. Technologies such as Fiber Channel are commonly used, providing
data transfers at four gigabits per second. This type of hard disk configuration allows for very large and
scalable solutions where large amounts of data can be stored with a high level of redundancy.
Server
Fiber channel
Tape
Figure 8.4.b. A typical SAN architecture where a fiber channel network ties all storage devices together and lets the servers share
the storage capacity.
Separate
storage
Network switch,
broadband router or
coprorate firewall
TCP/IP LAN
Server Server
Fiber channel
Fiber channel switch
RAID disk
array
Computer server with video
management software
Server
RAID disk
array
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