When you are planning storage, you need to determine how your
servers will access disks.
In some cases, you can attach disks directly to the servers that require
the storage.
However, in enterprises, storage often is in NAS or SANs, which
provide more flexibility.
Organizations have a wide variety of storage options, such as
DAS, NAS, and SANs.
DAS = DIRECT ATTACHED STORAGE
Almost all servers provide built-in storage, or direct-attached storage
(DAS).
DAS can include disks that are physically located inside the server
or that connect directly with an external array, or disks that connect to
the server with a universal serial bus (USB) cable or an alternative
connector.
DAS comes in various disk types, such as Serial ATA (SATA), serial
attached SCSI (SAS), or solid-state drive (SSD).
There are no network devices—hubs, switches, or routers—between
the DAS and the computer, but rather, the storage connects directly to
the server.
NAS = NETWORK ATTACHED STORAGE
NAS is storage that connects to a dedicated storage device and is then
accessed over the network.
NAS differs from DAS because the storage does not attach directly to
each individual server, but rather is accessible across a network to
many servers.
NAS devices typically provide file-level access to storage, which
means that data in the storage is accessible only as files and folders,
and you must use protocols such as Common Internet File System
(CIFS), Server Message Block (SMB), or network file system (NFS)
to access the files.
SAN = STORAGE AREA NETWORK
The third type of storage is a SAN, which is a high_speed network
that connects computer systems or host servers to high-performance
storage subsystems.
A SAN usually includes various components such as HBAs, special
switches to help route traffic, and storage disk arrays with logical unit
numbers (LUNs) for storage.
SANs provide block-level access. This means that rather than using a
file-access protocol to access disk contents as files, SANs write
blocks of data directly to the disks by using protocols such as Fibre
Channel over Ethernet or Internet SCSI (iSCSI).
HBA stands for Host Bus Adapter and is used to connect to block
level storage such as Fibre Channel, SATA or SCSI.
Most commonly this term is used when referring to Fibre Channel
HBAs in systems like Apples Xsan.
The main difference is the type of storage/switch you are connecting
to. HBA stands for Host Bus Adapter and is used to connect to block
level storage such as Fibre Channel, SATA or SCSI.
NIC stands for Network Interface Adapter and is used to connect
ethernet storage to a switch or server.
In computer storage, a logical unit number, or LUN, is a number
used to identify a logical unit, which is a device addressed by the
SCSI protocol or by Storage Area Network protocols that
encapsulate SCSI, such as Fibre Channel or iSCSI.
Volumes contain file systems in a NAS environment and LUNs in
a SAN environment.
A LUN (logical unit number) is an identifier for a device called a
logical unit addressed by a SAN protocol.
LUNs are the basic unit of storage in a SAN configuration. The
Windows host sees LUNs on your storage system as virtual disks.
iSCSI is a block protocol for storage networking and runs the very
common SCSI storage protocol across a network connection which is
usually Ethernet.
iSCSI, like Fibre Channel, can be used to create a Storage Area
Network (SAN).
LUN Types.
VDS supports five LUN types: simple, spanned, striped, mirrored,
and striped with parity.
Simple, spanned, and striped LUNs are non-fault tolerant; mirrored
and parity LUNs are fault tolerant.
Relationship between Fiber Optic Network Interface Card (NICs) and
HBAs
Because of the different transmission protocol, the network card can
be divided into three kinds, one is Ethernet card, the other is Fiber
Channel network card, and three is the iSCSI network card.
Ethernet Network Card – The name of the Ethernet Adapter, the
transmission protocol is an IP protocol, typically connected to an
Ethernet switch through a fiber optic cable or twisted pair.
The interface types are divided into optical and electrical ports.
Optical ports are generally transmitted through fiber optic cables, the
interface module is generally SFP (transmission rate GB)
and GBIC (1GB/s), the corresponding interface is SC, ST and LC.
The current commonly used interface type is RJ45, it is used to
connect with twisted pair, also has an interface with coaxial cable, but
now it is used less.
FC Network card – generally also called fiber optic network card,
scientific name Fibre Channel HBA.
The transport protocol is a Fiber Channel protocol and is typically
connected to a Fiber Channel switch through a fiber optic cable.
The interface type is divided into optical port and electrical port. The
optical interface is generally through the fiber optic cable for data
transmission, the interface module is generally SFP (transmission rate
2Gb / s) and GBIC (1Gb / s), the corresponding interface for the SC
and LC. The interface type of the electrical interface is generally DB9
pin or HSSDC.(HIGH SPEED SERIAL DATA CONNECTION)
iSCSI Network card – The name of the iSCSI HBA, the Transport
iSCSI protocol, and the interface type is the same as the Ethernet
card.
We say “fiber-optic network card” generally refers to the FC HBA
card, plug in the server, external storage with the fiber switch; and
optical Ethernet card is generally called “fiber Ethernet card” is also
inserted in the server, but it external Is the Ethernet switch with the
optical port.
