Disk Storage
Storage Area Networks (SAN)
In order to provide high-speed, continuous access to multiple
terabytes of data, a Storage Area Network (SAN) is required to overcome
throughput and data-sharing issues common in existing data networks.
In a SAN environment, storage devices such as tape libraries and
RAID arrays are connected to many kinds of servers via a high-speed
interconnection, such as Fibre Channel (FC), or IP-based approaches
such as iSCSI, or SOIP. These setups allows for any-to-any communication
among all devices on the SAN. It also provides alternative paths
from server to storage device. In other words, if a particular server
is slow or completely unavailable, another server on the SAN can
provide access to the storage device. A SAN also makes it possible
to mirror data, making multiple copies available. The high-speed
interconnection that links servers and storage devices essentially
creates a separate, external network hat's connected to the LAN
but acts as an independent network.
Network Attached Storage (NAS)
Network Attached Storage (NAS) is the term used to describe a LAN-attached
networked server with a stripped-down operating system, preconfigured
disk capacity, and integrated systems and storage software. The
NAS device operates much like a print server. It offloads the storage
function from the standard application server. It is a stable device,
easily installed and managed, which responds to file requests from
the other servers in the LAN.
Unlike a standard file server, a NAS system does not require the
purchase of separate hardware or software components, which would
need to be integrated onto the system before it is installed. NAS
devices use file protocols (typically Network File System (NFS)
or Common Internet File System [CIFS]) to communicate with the other
servers in the LAN. Both of these protocols are file protocols,
which do not support most database processes.
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