Hardware & the Machine room

Week 5 – Lecture 1

What is behind the wall plug for your workstation?

• Today we will look at the platform on which our Information System stands– LAN hardware– Server hardware– The machine room

What do we need?

• Reliability

• Performance

• Physical security

WAN WAN

Hubs

Switch

Router

Servers

The Internet is a network of networks

LANLANLANLAN

WAN

So how do we get the message?

Data link & Physical layers

TCP/IP TCP/IPNetwork & TransportLayers

Middleware MiddlewarePresentation & SessionLayers

ProcessOn Host A

Process onHost BApplication layer

Local Area Network• Hubs

– Physical layer - dumb– Propagates on all channels

• Switches– Data link Layer – MAC address level– Put message out on 1 channel– Fast, more intelligent, store & forward– Ethernet, ATM, FDDI etc– Collision zones

• Router– Network Layer device – IP level– Edge of network– Firewalls

Hubs

Switch

Router

Server hardware

CPU Memory(PrimaryStorage)

CommunicationsInterface

Disk(Secondary

Storage)

CPUCPU

Servers???

• Mainframes – IBMz900 zOS

• Mid-range – Sun Fire E25K Solaris/Unix

• Intel based – HP Proliant Windows 2000NT or Linux

                               

Scalability

• As demand on the server increases, how can it be upgraded to handle the increased load?

• Main components are – – Processor speed– Number of processors– Memory size and access speed– Data storage capacity and speed

Constraints on scalability

• Operating system• Number of processors permitted by the

architecture (e.g. Compaq DL580 has max of 4, Sun E10000 has max of 64)

• Memory access often limits effective utilisation of processors – increase in throughput is not linear

Number of processors

• A key issue in scalability

• Sun’s Solaris can now support up to 128 but architecture of Sun E10000 has 64 processor limit

• Until recently Windows NT/2000 NT could support 8 but now supports up to 32 and 64GB of memory.

• With the new IA64 processor the Windows/IA architecture will put performance as well as price pressure on the Unix/RISC based systems – within 2/3 years

• Unix continues to challenge the Mainframe market. They are also introducing automated management features

Windows NT/2000 & IA64

• IA 64 not designed to improve performance of IA 32 code

• Code has to be written to take advantage of it

• Major hardware limitation is probably now the PCI bus that connects the processors and memory to storage and controllers and expansion cards.

Multi processor servers

• Usually under the control of the one copy of the operating system

• But some high end machines (Sun E10000) have independent domains with each domain having its own copy of the operating system. Like two or more independent machines in the one box.

Number of processors is not the only issue. Memory management is critical

• Single processor

• Symmetric multi-processor – SMP – shared bus

• Symmetric multi-processor – SMP – cross bar

• NUMA

• Loosely coupled – MMP

• Clusters

SMP – shared bus is the most common

• But the bus provides a bottle neck to shared memory pool

• Memory access speed then declines and this prevents linear scalability

• TPC benchmarks show that often manufacturers get best performance at around 50% of maximum number of processors

SMP – Shared bus

CPU

CPU

CPU

CPU

Memorypool

I/O

Compaq DL580

SMP – Cross bar

CPU

CPU

CPU

CPU

Non Uniform Memory Access

CPU

CPU

CPU

CPU

Memory

I/O

Interface

CPU

CPU

CPU

CPU

Memory

I/O

Interface

Cross Bar

HP Super Dome & Sun E10000

Clusters

• Share nothing - Failover

• Share disk – requires distributed locking

• Share everything – slower than the bus of an SMP machine

LAN

High speedInterconnect

Clustering gives

• Scalability – workload can be distributed

• Availability – when one goes down the other takes over

• System management – managed as a single resource – particularly disk

Disk performance

• Capacity continues to double each year

• Speed made up of three elements– Rotational latency– Seek time– Transfer rate

Storage architectures

• Two emerging storage architectures– SAN – Storage Area Network

– NAS – Network Attached Storage

• SAN more closely coupled• NAS network orientated – higher latency• Semi independent for use with high end servers• High performance, large capacity, high availability,

data protection, management and back-up

Network Attached Storage

WEB Application Database NAS Server

Storage Area Networks

WEB Application Database

Fibre channel

File Server

Machine room environment

• Air conditioning

• Fire protection

• Reliable power

• Physical security