Module 03 - Physical Layer - part 1

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 Module: Physical Layer
Upon completion of this module, you should be able to:
• Describe compute system components and types
• Describe storage system architectures
• Describe network connectivity and the types of network
communication

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Cloud Computing Reference Model
Physical Layer

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 3
Physical Layer Overview
• The physical layer comprises physical
compute, storage, and network resources
• Compute systems execute software of
providers and consumers
• Storage systems store business and
application data
• Networks connect compute systems with
each other and with storage systems
– Networks also connect multiple data centers
or multiple clouds to one another

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 4
 Lesson: Compute System
This lesson covers the following topics:
• Key components of a compute system
• Software deployed on compute systems
• Types of compute systems

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Introduction to Compute System
• A computing platform (hardware, firmware, and software) that
runs platform and application software
– Executes the provider’s as well as the consumers’ software
– Typically x86-based servers or hosts
• Compute systems are provided to consumers in two ways:
– Shared hosting: Multiple consumers share compute systems
– Dedicated hosting: Individual consumers have dedicated compute
systems
• Typically providers use compute virtualization and offer
compute systems in the form of virtual machines

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 6
Key Components of a Compute System

• An IC that executes software programs by performing

Processor arithmetical, logical, and input/output operations

• A volatile data storage device containing the programs for

Random-Access Memory execution and the data used by the processor

• A semiconductor memory containing boot, power management,

Read-Only Memory and other device-specific firmware

• A PCB that holds the processor, RAM, ROM, network and I/O
Motherboard ports, and other integrated components, such as GPU and NIC

• A collection of microchips on a motherboard to manage specific

Chipset functions, such as processor access to RAM and to peripheral
ports

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Software Deployed on Compute Systems

Self-service portal • Enables consumers to view and request cloud services

Platform software • Includes the software that the provider offers through PaaS

Application software • Includes the applications that the provider offers through SaaS

Virtualization software • Enables resource pooling and creation of virtual resources

• Enables a provider to manage the cloud infrastructure and

Cloud management software services

• Includes a consumer’s platform software and business

Consumer software applications

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Types of Compute Systems
• Tower compute system
• Rack-mounted compute system
• Blade compute system

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Tower Compute System
• Built in an upright enclosure called a “tower”
• Has integrated power supply and cooling
• A group of towers occupies significant floor
space, requires complex cabling, and generates
noise from cooling units
• Deploying in large environments may involve
substantial expenditure

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 11
Rack-mounted Compute System
• Designed to be fixed on a frame called a “rack”
– A rack is a standardized enclosure with
mounting slots for vertically stacking compute
systems
• Simplifies network cabling, consolidates
network equipment, and reduces floor space
use
• Administrators may use a console mounted on
the rack to manage the compute systems

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 12
Blade Compute System
• Comprises an electronic circuit board with
only the core processing components
• Multiple blades are housed in a blade chassis
– The chassis provides integrated power supply,
cooling, networking, and management
• Blades are interconnected via a high speed
bus
• Modular design increases compute system
density and scalability

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 13
 Lesson Summary
During this lesson the following topics were covered:
• Key components of a compute system
• Software deployed on compute systems
• Types of compute systems: tower, rack-mounted, and blade

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 14
 Module 03 - Physical Layer - part 2

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Building the Cl oud Infrastruct ure 15
 Lesson: Storage System
This lesson covers the following topics:
• Types of storage devices
• Redundant Array of Independent Disks (RAID)
• Storage system architectures

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Introduction to Storage System
• A storage system is the repository for saving and retrieving
electronic data
• Providers offer storage capacity along with compute systems, or
as a service
– Storage as a Service enables data backup and long-term data
retention
• Cloud storage provides massive scalability and rapid elasticity
of storage resources
• Typically, a provider uses virtualization to create storage pools
that are shared by multiple consumers

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 17
Types of Storage Devices

• Stores data on a circular disk with a ferromagnetic coating

Magnetic disk drive • Provides random read/write access
• Most popular storage device with large storage capacity

• Stores data on a semiconductor-based memory

Solid-state (flash) drive • Very low latency per I/O, low power requirements, and very high
throughput

• Stores data on a thin plastic film with a magnetic coating

Magnetic tape drive • Provides only sequential data access
• Low-cost solution for long term data storage

• Stores data on a polycarbonate disc with a reflective coating

Optical disc drive • Write Once and Read Many capability: CD, DVD, BD
• Low-cost solution for long-term data storage

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 18
Redundant Array of Independent Disks (RAID)
RAID
A storage technology in which data is written in blocks across multiple disk
drives that are combined into a logical unit called a RAID group.

• Improves storage system performance by serving I/Os from

multiple drives simultaneously
• Provides data protection against drive failures
• Three key techniques used for RAID: striping, mirroring, and
parity

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RAID Technique: Striping
Striping
A RAID technique to spread data across multiple drives in order to use the
drives in parallel.

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RAID Technique: Mirroring
Mirroring
A RAID technique to store the same data simultaneously on two different
drives, yielding two copies of the data.

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 22
RAID Technique: Parity
Parity
A RAID technique to protect striped data from drive failure by performing a
mathematical operation on individual strips and storing the result on a
portion of the RAID group.

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 23
Common RAID Levels

RAID 0 • Striped set with no fault tolerance

RAID 1 • Disk mirroring

RAID 1+0 • Nested RAID (striping and mirroring)

RAID 3 • Striped set with parallel access and a dedicated parity disk

RAID 5 • Striped set with independent disk access and distributed parity

• Striped set with independent disk access and dual distributed

RAID 6 parity

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RAID 0
C
B Data from host
A

RAID Controller

A1 A2 A3 A4 A5
B1 B2 B3 B4 B5
C1 C2 C3 C4 C5

Data Disks

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 25
RAID 1 F
E
D
Data from host
C
B
A

RAID Controller

A A D D
B B E E
C C F F

Mirror Set Mirror Set

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 26
RAID 1+0
C
B Data from host
A

Striping
RAID Controller
Mirroring Mirroring Mirroring

A1 A1 A2 A2 A3 A3
B1 B1 B2 B2 B3 B3
C1 C1 C2 C2 C3 C3

Mirror Set A Mirror Set B Mirror Set C

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 27
RAID 3
C
B Data from host
A

RAID Controller

A1 A2 A3 A4 AP
B1 B2 B3 B4 BP
C1 C2 C3 C4 CP

Data Disks Dedicated Parity Disk

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 28
RAID 5
C
B Data from host
A

RAID Controller

A1 A2 A3 A4 AP
B1 B2 B3 BP B4
C1 C2 CP C3 C4

Single Distributed Parity

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RAID 6
C
B Data from host
A

RAID Controller

A1 A2 A3 AP AQ
B1 B2 BP BQ B3
C1 CP CQ C2 C3

Dual Distributed Parity

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 30
RAID Impacts on Performance

• In RAID 5, every write (update) to a disk manifests as four I/O operations (2 disk reads
and 2 disk writes)

• In RAID 6, every write (update) to a disk manifests as six I/O operations (3 disk reads and
3 disk writes)

• In RAID 1, every write manifests as two I/O operations (2 disk writes)

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 31
RAID Penalty Calculation Example
• Total IOPS at peak workload is 1200
• Read/Write ratio 2:1
• Calculate disk load at peak activity for:
– RAID 1/0
– RAID 5

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 32
RAID Penalty Calculation Example
• For RAID 1/0, the disk load (read + write)
= (1200 x 2/3) + (1200 x (1/3) x 2)
= 800 + 800
= 1600 IOPS
• For RAID 5, the disk load (read + write)
= (1200 x 2/3) + (1200 x (1/3) x 4)
= 800 + 1600
= 2400 IOPS

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 33
Common RAID Levels

RAID 0 • Striped set with no fault tolerance

RAID 1 • Disk mirroring

RAID 1+0 • Nested RAID (striping and mirroring)

RAID 3 • Striped set with parallel access and a dedicated parity disk

RAID 5 • Striped set with independent disk access and distributed parity

• Striped set with independent disk access and dual distributed

RAID 6 parity

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 34
Data Access Methods

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 35
Storage System Architecture
• Storage system architectures are based on the data access
methods
• Common storage system options are:
– Block-based
– File-based
– Object-based

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 36
 Module 03 - Physical Layer - part 3

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Building the Cl oud Infrastruct ure 37
Block-based Storage System
• Enables creating and assigning storage volumes to compute
systems
– Compute system discovers the volumes as local drives
– Required file system can be created on the volumes

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 38
 Key Components of an ISS

Block-based Storage System

Host
Front End Back End Physical Disks

Cache
Connectivity
Storage
Network

EMC Proven Professional. Copyright © 2012 EMC Corporation. All Rights Reserved. 40
 Key Components of ISS: Front End

Block-based Storage System

Host
Front End Back End Physical Disks

Cache

Storage
Network

Ports Controllers

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 Key Components of ISS: Cache

Block-based Storage System

Host
Front End Back End Physical Disks

Cache

Storage
Network

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 Read Operation with Cache
Data found in cache = Read hit

Data found in cache

1. Read Request

2. Data sent to host

Data not found in cache = Read miss

Data not found in cache

1. Read Request 2. Read Request

4. Data sent to host 3. Data copied to cache

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 Write Operation with Cache
Write-through cache

Cache

1. Data write 2. Data write

4. Acknowledgment 3. Acknowledgment

Write-back cache

Cache

1. Data write 3. Data write

2. Acknowledgment 4. Acknowledgment

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 Cache Management: Algorithms
• Least recently used (LRU)
 Discards data that have not been accessed for a long time
• Most recently used (MRU)
 Discards data that have been most recently accessed

New Data

Cache LRU/MRU Data

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 Cache Management: Watermarking
• Manages I/O burst through flushing process
 Flushing is the process of committing data from cache to the disk
• Three modes of flushing to manage cache utilization are:
 Idle flushing
 High watermark flushing
 Forced flushing
100
%
HWM

LWM

Idle flushing High watermark flushing Forced flushing

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 Cache Data Protection
• Protects data in the cache against power or cache failures:
 Cache mirroring
 Provides protection to data against cache failure
 Each write to the cache is held in two different memory locations on two independent memory
cards
 Cache vaulting
 Provides protection to data against power failure
 In the event of power failure, uncommitted data is dumped to a dedicated set of drives called
vault drives

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 Key Components of ISS: Back End

Intelligent Storage System

Host
Front End Back End Physical Disks

Cache

Storage
Network

Controllers Ports

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 Key Components of ISS: Physical Disks

Intelligent Storage System

Host
Front End Back End Physical Disks

Cache

Storage
Network

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 Assigning Storage to Host
Storage Provisioning

It is the process of assigning storage resources to hosts based on capacity,

availability, and performance requirements of applications running on the
hosts.

• Can be performed in two ways:

 Traditional storage provisioning
 Virtual storage provisioning

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 Traditional Storage Provisioning
Host 1
Intelligent Storage System
LUN 0
Physical Disks
Front End Back End (RAID Set)
Cache
LUN 0

Storage
Network

LUN 1

LUN 1

Host 2

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 LUN Expansion
Base LUN Component LUN

MetaLUN +
It is a method to expand LUNs that require
additional capacity or performance.
• Created by combining two or more LUNs
• MetaLUNs can either be concatenated or striped
• Concatenated metaLUN Concatenated MetaLUN

 Provides only additional capacity but no

performance Base LUN Component LUN
 Expansion is quick as data is not restriped
+
• Striped metaLUN
 Provides capacity and performance
 Expansion is slow as data is restriped

Striped MetaLUN

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 Virtual Storage Provisioning
Host 1 10 TB

Thin LUN 0
Host
Reported Capacity
Intelligent Storage System
3 TB
Physical Disks
Allocated
Front End Back End (Shared Pool)
Thin LUN 0
Cache

Storage
Network

Thin LUN 1

10 TB

Thin LUN 1
Host
Reported Capacity

4 TB
Host 2 Allocated

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 Traditional Provisioning vs. Virtual Provisioning

150 GB
Available
Capacity
1500 GB 1650 GB
800 GB
800 GB or 550 GB or
550 GB 1.65 TB
1.5 TB 500 GB
500 GB 600 GB Available
Allocated Allocated
400 GB Unused
Unused Capacity
500 GB Capacity
Allocated
Unused
Allocated Capacity
Unused
Capacity
Capacity 350 GB
350 GB
100 GB 200 GB 100 GB 50 GB 200 GB Actual data
Data 50 GB Data Data Actual data Allocated Allocated Allocated
Thin LUN
Storage System Thin LUN 1 Thin LUN 3 Storage System
LUN 1 LUN 2 LUN 3 2
2 TB 2 TB

Traditional Provisioning Virtual Provisioning

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 Lesson Summary
During this lesson the following topics were covered:
• Types of persistent data storage devices
• RAID and RAID techniques: striping, mirroring, and parity
• Storage system architectures: block-based, file-based,
object-based

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 55
 Module 03 - Physical Layer - part 4

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Building the Cl oud Infrastruct ure 56
 Lesson: Network
This lesson covers the following topics:
• Types of network communication
• Compute-to-compute communication
• Compute-to-storage communication
• Storage area network (SAN) classification
• Inter-cloud communication

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 57
Introduction to Networking
• Networking enables data transfer and sharing of IT resources
between nodes across geographic regions
• Cloud consumers require a reliable and secure network to
connect to a cloud and access cloud services
• Network connectivity also enables resource aggregation and
service mobility across cloud data centers
• Multiple clouds may be inter-connected to enable workloads to
be moved or distributed
– For example: cloud bursting in a hybrid cloud model

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 58
Types of Network Communication
• Based on the nodes connected by a network, the network
communication is broadly categorized as:
– Compute-to-compute communication
– Compute-to-storage communication
– Inter-cloud communication

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 59
Compute-to-compute Communication
• Interconnecting physical compute
systems enables compute-to-compute
communication
• Compute-to-compute communication
typically uses IP-based protocols
• Compute systems connect to a network
through physical network card(s)
• Physical switches and routers are
common interconnecting devices

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 60
Compute-to-storage Communication
Storage Area Network (SAN)
A network that interconnects storage systems with compute systems,
enabling the compute systems to access and share the storage systems.

• Based on the protocols they support:

– Fibre Channel SAN (FC SAN)

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 61
FC SAN
FC SAN
A SAN that uses Fibre Channel (FC) protocol to
transport data, commands, and status information
between compute and storage systems.

• FC provides block-level access to storage

• FC offers data transfer speeds up to 16 Gbps
• Theoretically, an FC SAN can connect
approximately 15 million nodes

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 62
Inter-cloud Communication

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 63
 Lesson Summary
During this lesson the following topics were covered:
• Types of network communication
• Compute-to-compute communication
• Compute-to-storage communication (SAN)
• Inter-cloud communication

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 64
 Module Summary
Key points covered in this module:
• Compute system components and types
• Types of storage devices, RAID techniques, and storage
system architectures
• Network connectivity and the types of network
communication

© Copyri ght 2014 EMC Corporation. Al l rights res erved. Module: Physical Layer 65