CLIENT SERVER COMPUTING –DATA STORAGE II ME CSE

2015-16 ODD SEMESTER (III SEMESTER)

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TopicsMagnetic DiskMagnetic TapeCD ROMWormOptical DiskMirrored DiskFault ToleranceRAID

Network Protection Devices

Power Protection DevicesClient Server System

DevelopmentRemote System

Management

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Magnetic Disk• There are various types of auxiliary storage; all of them

involve some type of magnetic disk.• It uses magnetism to store the data on a magnetic surface.• The advantages associated with such type of storage media

– high storage capacity, – reliable and – provides direct access to the data.

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Magnetic Disk• The available magnetic

disks are – Diskette

–Floppy disk

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Magnetic Disk– Hard Disk

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Magnetic Disk• What happens when a disk is formatted?

– Whether all data is erased? – Surfaces are checked for physical and magnetic defects. – A root directory is created to list where things are on the disk.– The capacity of a magnetic disk depends on several factors.

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Magnetic Tape• Magnetic tape is a secondary storage device, generally

used for backup purposes.• They are permanent and not volatile by nature.• The speed of access can be quite slow, however, when the

tape is long and what you want is not near the start.• So this method is used primarily for major backups of large

amounts of data.

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Magnetic Tape• The format method will

determine the some important characteristics like–Density –Block–Gap

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CD-ROM• CD-ROM (Compact Disc, read-only-memory) is an adaptation of

the CD that is designed to store computer data in the form of text and graphics, as well as hi-fi stereo sound.

• Although the disc media and the drives of the CD and CD-ROM are, in principle, the same, there is a difference in the way data storage is organized.

• Two new sectors were defined–CD-ROM Mode 1 for storing computer data.–CD-ROM Mode 2 for compressed audio or video/graphic data.

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CD-ROM• Data Encoding and Reading

– The CD-ROM, like other CD adaptations, has data encoded in a spiral track beginning at the center and ending at the outermost edge of the disc. 

– The spiral track holds approximately 650 MB of data. That's about 5.5 billion bits.

– The track pitch can range from 1.5 to 1.7 microns, but in most cases is 1.6 microns.

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CD-ROM• Constant Linear Velocity (CLV)

– CLV  is the principle by which data is read from a CD-ROM.– Principle states that the read head must interact with the data

track at a constant rate, whether it is accessing data from the inner or outermost portions of the disc. 

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WORM• WORM (write once, read many) is a data storage

technology that allows information to be written to a disc a single time and prevents the drive from erasing the data.

• The discs are intentionally not rewritable, because they are especially intended to store data that the user does not want to erase accidentally.

• Used for the archival purposes of organizations such as government agencies or large enterprises. 

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WORM• The discs have varied in size from 5.25 to 14 inches wide,

in varying formats ranging from 140MB to more than 3 GB per side of the (usually) double-sided medium.

• Data is written to a WORM disc with a low-powered laser that makes permanent marks on the surface.

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WORM Top: the hybrid

organic/inorganic semiconductor WORM memoryBottom: Diagram of the WORM memory element used in this study Also shown is the chemical structure of the two-component electrochromic polymer PEDOT (polyethylenedioxythiophene (PEDT): polystyrene sulphonic acid (PSS) 

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Optical DiskAn optical disc holds much more data.The greater control and focus possible with laser beams (in

comparison to tiny magnetic heads) means that more data can be written into a smaller space.

An optical disc is an electronic data storage medium that can be written to and read using a low-powered laser beam.

Storage capacity increases with each new generation of optical media. Emerging standards, such as Blu-ray, offer up to 27 gigabytes (GB) on a single-sided 12-centimeter disc.

Optical discs are inexpensive to manufacture.

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Variants Read-Only (Factory Pressed)•Read-only discs are pressed from a master at the time of manufacture and cannot be erased.CD-ROM, DVD-ROM, DVD-Video and BD-ROM (Blu-ray).Write-Once (Burnable)•Write-once discs are recorded in the user's environment but cannot be erased. They include the CD-R, DVD-R, DVD+R, BD-R (Blu-ray), WORM discs, as well as magneto-optic (MO) discs in WORM mode.Rewritable (Phase Change and Magneto Optic)•Rewritable discs can be written and re-written numerous times. Employing phase change technology, consumer-oriented products include CD-RW, DVD-RAM, DVD-RW, DVD+RW and BD-RE (Blu-ray)

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RAIDRedundant Arrays of Independent DisksMotivation

Typical memory bandwidths 150 MB/sec

Typical disk bandwidths 10 MB/sec

Result: I/O-bound applications limited by disk bandwidth (not just by disk latency!)

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Solution: Exploit ParallelismStripe the data across an

array of disksmany alternative striping

strategies possibleExample: consider a big

file striped across N disksstripe width is S byteshence each stripe unit is

S/N bytessequential read of S bytes

at a time

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Performance BenefitSequential read or write of

large fileapplication (or I/O buffer

cache) reads in multiples of S bytes

controller performs parallel access of N disks

aggregate bandwidth is N times individual disk bandwidth

(assumes that disk is the bottleneck)

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N concurrent small read or write requests

randomly distributed across N drives (we hope!)common in database and Web server environments

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RAID ApproachesMany alternative approaches to achieving this redundancy

RAID levels 1 through 5

hot sparing allows reconstruction concurrently with accesses

Key metrics to evaluate alternativeswasted space due to redundancylikelihood of “hot spots” during heavy loadsdegradation of performance during repair

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RAID Level 1Also known as “mirroring”

To read a block:read from either data disk or backup

To write a block:write both data and backup disksfailure model determines whether

writes can occur in parallel

Backups can be located far way: safeguard against site failure

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RAID Levels 2 & 3These are bit-interleaved

schemesIn Raid Level 2, P contains

memory-style ECCIn Rail Level 3, P contains

simple parityRarely used today

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RAID 4Block-interleaved parityWasted storage is small:

one parity block for N data blocks

Key problem: parity disk becomes a hot

spotwrite access to parity disk

on every write to any block

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RAID 5Rotated parityWastage is small: same as

in Raid 4Parity update traffic is

distributed across disks

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RAID 5 Actions

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Network Protection Device /Security Appliance Security Appliance or Network Protection is used to control

network access of a computer

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Network Protection DevicesNetwork Protection Devices

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• It is designed to protect computer networks from unwanted traffic• Examples include–CyberRoam Security devices, Firewalls ,Secured Routers etc.,

• 4 Types of Network Protection devices –Active devices –Passive devices –Preventative devices –Unified Threat Management (UTM)

Active devices - block unwanted traffic. Eg: such devices are firewalls, anti virus scanning devices, and content filtering devices.

Passive devices - detect and report on unwanted traffic, such as intrusion detection appliances.

Preventative devices - scan networks and identify potential security problems (such as penetration testing and vulnerability assessment appliances).

Unified Threat Management (UTM) appliances combine features together into one system, such as some firewalls, content filtering, web caching etc.

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Eg1: CyberRoam Security Device• Available as UTMs and Next Generation Firewalls, deliver enterprise-class network security with stateful inspection firewall, VPN and IPS. • This ensures high levels of network security, network connectivity, continuous availability.• Offers enterprise-class security and high flexibility with protection against blended threats, malware, Trojans, DoS, DDoS, IP spoofing attacks, spam, intrusions and data leakage.• http://www.cyberoam.com/networksecurity.html

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Eg2: Cisco PIX (Private Internet eXchange)

• IP firewall and network address translation (NAT)appliance• First commercially available firewall product to introduce protocol specific filtering with the introduction of the "fixup" command• PIX "fixup" capability allows the firewall to apply additional security policies to connections • Incorporates IPSec VPN gateway functionality

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Power Protection Devices and its need?

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• Power protection system - connected to a single power-protection source, such as an uninterruptible power supply (UPS). • First, power-protection equipment must contend with an increasingly wide range of system configurations. –Servers, workstations, routers, hubs, bridges and other sensitive components must all be taken into consideration.

• Second, as computer-based systems become more integral to telecommunications operations a minor power problem has catastrophic effects

Uninterruptible power supply ( UPS)

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• Uninterruptible power source, UPS or battery/flywheel backup - electrical apparatus that provides emergency power when the input power source, typically mains power, fails. • A UPS differs from an auxiliary or emergency power system or standby generator• Provides near-instantaneous protection from input power interruptions, by supplying energy stored in batteries,supercapacitors, or flywheels. • The on-battery runtime of most uninterruptible power sources is relatively short but sufficient to start a standby power source or properly shut down the protected equipment.

Power Management (PM)

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• Typically used to protect hardware such as computers, data centers, telecommunication equipment or other electrical equipment• Three general categories of modern UPS systems are

–on-line,–line-interactive and–Standby

• Power management (PM) requires the UPS to report its status to the computer it powers via a communications link such as a serial port, Ethernet and Simple Network Management Protocol, GSM/GPRS or USB• A subsystem in the OS that processes the reports and generates notifications, PM events, or commands an ordered shut down.

System Administration•System administration is the field of work in which someone manages one or more systems like software, hardware, servers or workstations. • Its goal is ensuring the systems are running efficiently and effectively.•Duties of a system administrator.

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System Administrator's Responsibilities • Morning checks of systems/software.• Performing backups of data.• Applying operating system updates, and configuration changes.• Installing and configuring new hardware/software.• Adding/deleting/creating/modifying user account information, resetting passwords,

etc.• Answering technical queries.• Responsibility for security.• Responsibility for documenting the configuration of the system.• Troubleshooting any reported problems.• System performance tuning.• Keeping the network up and running.• Technical support

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Reliability, Availability and Serviceability (RAS)Reliability, Availability and Serviceability (RAS) is a set of related attributes that must be considered when designing, manufacturing, purchasing or using a computer product or component.•The term was first used by IBM to define specifications for their mainframe s and originally applied only to hardware .•Reliability-> ability of a computer-related hardware or software component to consistently perform according to its specifications.•In theory, a reliable product is totally free of technical errors.•In practice, vendors commonly express product reliability as a percentage.•Availability ->ratio of time a system or component is functional to the total time it is required or expected to function.•Serviceability -> expression of the ease with which a component, device or system can be maintained and repaired.

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Key elements of RAS are:•Over-engineering, which is designing systems to specifications better than minimum requirements.•Duplication, which is extensive use of redundant systems and components.•Recoverability, which is the use of fault-tolerant engineering methods.•Automatic updating, which is keeps OSs and applications current without user intervention.•Data backup , which prevents catastrophic loss of critical information.•Data archiving , which keeps extensive records of data in case of audits or other recovery needs.

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Network Management• Network management refers to the broad subject of managing computer

networks. There exists a wide variety of software and hardware products that help

network system administrators manage a network.• Network management covers a wide area, including:

– Security: ensuring that the network is protected from unauthorized users.

– Performance: eliminating bottlenecks in the network.– Reliability: making sure the network is available to users and

responding to hardware and software malfunctions.

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Architecture

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NETWORK MANAGEMENT SYSTEM Network management system (NMS) is a set of hardware

or software tools that allow an IT professional to supervise the individual components of a network within a larger network management framework.

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NMSNetwork management system components assist with: Network device discovery - identifying what devices are present on a network.

Network device monitoring - monitoring at the device level to determine the health of network components and the extent to which their performance matches capacity plans and intra-enterprise service-level agreements (SLAs).

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NMSNetwork performance analysis - tracking performance indicators such as bandwidth utilization, packet loss, latency, availability and uptime of routers, switches and other Simple Network Management Protocol (SNMP) -enabled devices.

Intelligent notifications - configurable alerts that will respond to specific network scenarios by paging, emailing, calling or texting a network administrator.

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SNMP Simple Network Management Protocol (SNMP) is the protocol governing network management and the monitoring of network devices and their functions.

SNMP uses the User Datagram Protocol (UDP) and is not necessarily limited to TCP/IP networks.

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ComponentsAn SNMP-managed network consists of three key components:

Managed device - A managed device or the network element is a part of the network that requires some form of monitoring and management e.g. routers, switches, servers, workstations, printers, UPSs, etc...

Agent — software which runs on managed devices. Network management station (NMS) — software which runs on the manager.

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Principle of SNMP Communication

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Remote Systems Management Security

REMOTE ADMINISTRATION:• Remote administration refers to controlling a computer

from a remote location.• Software that allows remote administration is becoming

increasingly common and is often used when it is difficult or impractical to be physically near a system in order to use it.

• A remote location may refer to a computer in the next room or one on the other side of the world.

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Security requirements• Confidentiality• Integrity• Authentication• Non-repudiation• Availability• Access control

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Security services

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What are Remote Management Services?

• Cisco Remote Management Services (RMS) enable us to simplify the adoption and management of technologies.

• Through maximized high performance and increasedavailability and use of these solutions, we can realize our return on technology investments faster with proactive,continuous remote monitoring and management of the network

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RMS • With RMS, we can anticipate, identify and resolve

issuesfaster and with greater accuracy while retaining as much visibility and control as our desire.

• Our renowned support comes from certified Cisco experts with extensive experience across a broad spectrum of technologies combined with a wealth of best practices, Cisco intellectual capital, smart capabilities and service automation that truly differentiate the customer experience.

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Remote Management Services Overview

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RMS ValuePeople, Tools and Processes• Utilizing ITIL methodologies and Cisco best practices to

fully utilize the depth of our global user experiences to trend, analyze and quickly resolve issues faster.

• This increases the value of our investment by improving the user experience with clearly defined processes.

• The power of our industry leading standards, tools and automation specifically address your support challenges, effectively reaching resolution faster and consistently managing complex enterprise environments

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RMS ValuePeople, Tools and Processes

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NETWORK MANAGEMENT ISSUES• Failure to properly configure firewalls– In a good network design, an enterprise should protect its

systems with both network and host firewalls.– Failing to properly configure firewalls creates a foothold for

the exploitation of other vulnerabilities.• Failure to authenticate network users.– It's a good idea to use some form of authentication

technology, such as 802.1x, to ensure that devices connecting to your network are associated with an authorized user.

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• Use of weak (or no) wireless encryption.– Believe it or not, many enterprises still use WEP encryption to

"protect" their networks.–WEP encryption is fundamentally flawed and should never be

relied upon to secure a wireless network. Use WPA encryption instead.

• Failure to patch.– Everyone knows that it's important to apply vendor security

patches to systems and applications.– In fact, a recent study showed that many Oracle administrators

have never applied patches to their systems.– This is a bad idea, as hackers keep a close eye on security

bulletins, looking for exploitable flaws. 56