Storage Networking - IMPACT

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23 Οκτ 2013 (πριν από 4 χρόνια και 21 μέρες)

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Storage Networking

By James A Pendleton, Jr.

Types of Storage area Networks


SAN


Characteristics


Benefits


Disadvantages




NAS


Characteristics


Benefits


Disadvantages


Others: DAS, IAS, etc.



General SAN Components


FC Switch



Host Bus Adapter



ISL(s)



Attached Storage

SAN Topology


5 Primary Types


Star (hub
-
and
-
spoke)


Linear (bus/cascade)


Circular (ring/loop)


Tree


Mesh


Full Mesh


Partial Mesh


Six primary topologies can
be combined to form a
hybrid topology.



Star

In a Star Topology, all devices are
connected to a central hub. They
are relatively easy to install and
manage, but bottlenecks are
common because of the need for
all data to pass through the hub.
The central hub can also stand as
a single point of failure. One work
around for this is to distribute the
star network across multiple hubs.

Linear

A Linear Topology has all devices connected to a central cable, called the bus or
backbone. Bus networks are relatively inexpensive and easy to install for small
networks. Ethernet systems tend to use a bus topology, as do most mainframes.
They tend to not scale too well. You can minimize problems with scalability by
distributing the network.

Circular

Circular Topology connects all devices to one another in the shape of a closed loop, so

that each device is connected directly to two other devices, one on either side of it.

Ring topologies are relatively expensive and difficult to install, but they

offer high bandwidth and can span large distances.

Tree

A tree topology combines characteristics of linear
bus and star topologies.

It consists of groups of star
-
configured
workstations connected to a

linear bus backbone cable.

Tree topologies are highly edge
-
core
friendly. Core
-
edge design is used

to build a large san using small switches.

They can be expensive and complex to
implement and maintain. Strict tree has a
problem with redundancy so ISLs are used
to eliminate Point of Failures.

Mesh Topologies


Full mesh topology occurs
when every node has a circuit
connecting it to every other
node in a network. Full mesh
is very expensive to
implement but yields the
greatest amount of
redundancy, so in the event
that one of those nodes fails,
network traffic can be directed
to any of the other nodes. Full
mesh is usually reserved for
backbone networks due to
price.


Partial mesh topology is less
expensive to implement and
yields less redundancy than full
mesh topology. With partial
mesh, some nodes are
organized in a full mesh
scheme but others are only
connected to one or two in the
network. Partial mesh topology
is commonly found in peripheral
networks connected to a full
meshed backbone.

Network Reference Model


The OSI Reference model


Layer 1
-

physical layer:


Layer 2
-

data
-
link layer


Layer 3
-

network layer


Layer 4
-

transport layer


Layer 5
-

session layer


Layer 6
-

presentation layer


Layer 7
-

application layer

OSI in action: Web Page

It is not required that that each device meets every layer, in fact many devices
do not.

OSI in a network

Approach to engineering a SAN:


Physical Restrictions


Data Locality


Connectivity


Capacity


Heterogeneous [het
-
er
-
uh
-
jee
-
nee
-
uh s]
Platforms& O/S


Scalability and Migration


Backup and Restore


Data Availability


Disaster Tolerance


Switch and Hop Counts


Oversubscription


Performance and Application workloads


Manageability


Fabric Zoning


Selective Storage Presentation


SAN Security


What usually overrides all correct
and logical engineering decisions: