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SAS 712 U Series User Manual
NAS provides both storage and a file system. This is often contrasted with SAN (Storage Area
Network), which provides only block-based storage and leaves file system concerns on the "client"
side. SAN protocols are SCSI, Fibre Channel, iSCSI, ATA over Ethernet (AoE), or HyperSCSI.
One way to loosely conceptualize the difference between a NAS and a SAN is that a NAS appears
to the client OS (operating system) as a file server (the client can map network drives to shares on
that server) whereas a disk available through a SAN still appears to the client OS as a disk, visible in
disk and volume management utilities (along with client's local disks), and available to be
formatted with a file system and mounted.
iSCSI Concepts
iSCSI (Internet SCSI) is a protocol which encapsulates SCSI (Small Computer System Interface)
commands and data in TCP/IP packets for linking storage devices with servers over common IP
infrastructures. iSCSI provides high performance SANs over standard IP networks like LAN, WAN or
the Internet.
IP SANs are true SANs (Storage Area Networks) which allow several servers to attach to an infinite
number of storage volumes by using iSCSI over TCP/IP networks. IP SANs can scale the storage
capacity with any type and brand of storage system. In addition, it can be used by any type of
network (Ethernet, Fast Ethernet, Gigabit Ethernet, and 10 Gigabit Ethernet) and combination of
operating systems (Microsoft Windows, Linux, Solaris, Mac, etc.) within the SAN network. IP-SANs
also include mechanisms for security, data replication, multi-path and high availability.
Summary of Contents for SAS 712U
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