Download Storage-2017-1 - Lesmahagow High School

Technical
Implementation
STORAGE
Cloud Systems and Server Provision
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Description and benefits of distributed storage.
Description and benefits of offline storage.
Description of the advantages/dis-advantages of
Cloud systems compared to local server provision
including:
o Cost, accessibility, maintenance
Description and comparison between public, private
and hybrid cloud systems.
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Description of backup systems and strategy including:
o schedule — frequency, differential, incremental
o media — DAT, DTL, optical
o location — on-site, off-site repository, cloud
o mirroring (RAID)
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Description and exemplification of the appropriate type of
storage required for a specific information system
including:
o type of device, capacity, interface type and data
transfer speed
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Description and exemplification of current trends in
storage systems.
What is a backup?
When Would a backup be used?
Capacity Table
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Put the following computer storage amounts in
order. Smallest first:
Terabyte
Byte
Kilobyte
Gigabyte
Exabyte
Bit
Megabyte
Petabyte
Distributed Storage
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Distributed storage is when data is stored
across a number of different servers that are
located in different places.
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To the user, it seems like all of their data is
stored in one location but in reality data is
distributed across a number of servers that are
working at the same time to provide the user
with on demand access.
Distributed Storage (continued)
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Cloud storage systems often make use of
distributed storage.
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Some of your files may be stored on a server in
Glasgow, while some other files are on a server
in Edinburgh. However, it would be more
common for the same file to be replicated on
two different servers. This has benefits......
Distributed Storage - Benefits
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Ability to distribute the load of network traffic across more
than one server.
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It is easier to expand a storage network.
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If you make a request to access files it would be possible to direct
that request to both servers. One server may be busy dealing with
lots of requests while the other is less busy. This would allow your
cloud provider to give you access to your files from the quieter
server.
Rather than having to buy new servers to cope with demand. It is
possible to hire use of servers from third parties. The ability of an
organisation to quickly request more or less storage space for
cloud services is known as scalability.
Data is backed up instantaneously.
If one of the servers has a problem another can take over.
Off-line Storage
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Offline storage is storage that must be physically
connected or inserted into a computer system.
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Examples:
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portable hard disk, CDs, DVDs, USB flash drives and SD
cards.
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These storage mediums are portable and
compatible with a range of systems.
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Offline storage can also be used to create
backups.
Off-line Storage - Benefits
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Can be cheaper then storing on-line
Not as easy to expand as no cloud based services
can be used.
Less reliance on an internet connection
Cloud Vs Local
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Cloud technology relies on using lots of servers in
various locations across a wide area network.
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Users login to access files from any device that is
connected to the internet.
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E.g. iCloud set up
Local servers are part of a local area network and
provide users of that particular network with
access to files stored on the server. Once a user
logs in to a client, the local server will make their
files available to them.
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E.g. Lanark Grammar School set up
Cloud Vs local Accessibility
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Card Task Match up and staple to the end of
the slides
Cloud Vs local Accessibility
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Cloud
An internet connection is necessary to use all of the features of the cloud.
24/7 instant access is available where an internet connection does exist.
Users can access their cloud storage space from numerous devices, often
using apps or dedicated software.
Local
Using local storage it is usually necessary to be working on a client
system within the network.
Some systems do allow external access to some files and services.
Access in this way often depends upon use of browser software and may
not be as convenient on mobile or tablet devices as use of dedicated
cloud apps.
The main drawback of local storage is the need for users to login in to a
client. This means users are restricted to the physical boundary of a local
area network and are unlikely to be able to access all services from out
with the network.
Cloud Vs local Maintenance
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Cloud service providers are responsible for any
maintenance when using their services.
A user will be unaware of maintenance taking
place because cloud services use distributed data
storage. Copies of their data are stored in multiple
locations to protect against maintenance leading
to a loss of access.
If a local server is down and requires maintenance
work it is very unlikely that users will be able to
access their data, certainly in the short term.
It is also the case that the business is responsible
for any ongoing maintenance contact
Public Cloud
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Applications and storage are delivered through
an internet connection.
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Amazon’s EC2, Blue Cloud, Sun Cloud, Google app
engine, Windows Azure Services
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Organisation does not need to purchase their
own servers and manage all services internally.
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They can hire use of servers and services on a
needs basis, making scalability easier.
Private Cloud
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A physical server that is within the companies own
network.
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Infrastructure used for only one organisation.
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Company pays for the hardware, software and
maintenance.
Used where companies don’t want to lose control of their
own data.
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Perceived to be more secure.
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Costly & takes time to set up (design, purchase, install &
maintain)
Hybrid Cloud
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A combination of public and private cloud
systems.
Advantages of using a hybrid cloudo
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Companies will have sensitive data that they wish to
keep on a private cloud.
They want to give employees access to applications
wherever they are in the world so will use a public cloud.
Don’t need to purchase new hardware to use a public
cloud.
Backup Systems & Strategy
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System failures can occur.
A good backup strategy will be able to deal with
a system failure.
Backup Strategy will take into account –
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What data needs to be backed up? Programs and
operating systems could be reinstated from disks
so don’t require to be backed up.
The storage requirements.
The type of media – hard disks, magnetic tape,
cloud back-up system.
Schedule of when the backup should be made.
Backup strategy – Schedule Frequency
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Full – all data in the system is copied regardless or
whether or not it has changed since it was last backed
up.
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Differential – only the data that has changed since the
last full backup is stored even if a differential backup
has happened in-between
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Can be time consuming
Saves storage space and time
Slightly inefficient as the first differential backup could have
up to date copies of many files that are then copied again
during the second differential backup.
Incremental – only changes made since the last backup
of any kind are stored.
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Takes less time that differential and takes less storage
space
Backup TaSK
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Perform a full backup of the original data.
Now edit the first line of the address to ‘Short
Lane’
Perform a differential backup.
Now edit the first line of the address to ’34’
Perform a differential backup.
Perform another differential backup.
Perform an incremental backup.
Common System & Recovery
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Full backups to happen once a week
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Then either a differential backup or incremental
backup happening on a daily basis.
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To recover data, it will be necessary to have access
to the most recent full backup and then either the
most recent differential backup or all incremental
backups that took place since the last full backup.
Backup strategy - media
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DAT - Digital Audio Tape and is a form of
magnetic tape backing storage.
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Tapes look like traditional compact cassettes
but record in digital format rather than in
analogue.
Capable of storing up to 160GB of
uncompressed data when using the DAT 320
standard.
DLT - Digital Linear Tape is another form of
magnetic tape storage that can also
support up to 160GB of data.
Using DAT or DLT is a cost effective method
of backup as cassettes and drives are
cheaper than using dedicated servers or
virtual servers.
Neither technology is likely to be used
outside of industry.
Backup strategy - media
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Optical backup involves using optical discs such as CDs, DVDs
and Blu-Ray discs. Optical backup is often used for archiving.
Archived data is data that is backed up for future reference
Disadvantage of optical storage is it’s relatively small
capacities. It can also be inconvenient to have to keep
inserting and removing discs when trying to back up lots of
data.
Duke boxing can alleviate this issue by allowing thousands of
discs to be added to different slots before a backup begins.
Backup strategy - Location
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On-site - backup is stored within the same premises as the
live data.
Benefits:o cost and ease of access in the event that the backup is
needed.
o No need to be connected to the internet as there would
be with cloud backups.
o Full control of when backup and maintenance takes
places is always retained by an organisation when using
onsite backups as is security of data.
Disadvantage:-Both the live data on a server and the backup
system could be destroyed in the event of fire or water
damage. Malicious damage or theft is also a risk of using
onsite backups.
Backup strategy - Location
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Off-site repository - storing backups away from an
organisation and the active server or data.
Benefits:o
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Remove the risk of physical damage that can be caused by
fire, water or malicious acts onsite. If made available online,
It is also possible to access backups from any location
where there is an internet connection.
Distributed data storage can also be used to create
several different backups all stored in different locations.
This can either be used as a way to split the load of the
backup across several devices or to act as a strategy for
ensuring that backups are accessible from different
servers or repositories.
Disadvantage
 lose
control of some security and maintenance tasks.
Backup strategy - Location
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Cloud - version of offsite storage that is almost
guaranteed to make use of a distributed data storage
model.
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Cloud backup depends on access to the internet and the
use of software that provides access to the cloud.
RAID – Mirroring
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RAID - Redundant Array of Independent Disks.
Data is written to more than one drive at the same time in
an identical fashion (mirror). This also means that data can
be read from more than one drive, as requests can be sent
to all mirror drives simultaneously.
The main issue with using mirror drives is that of accidental
deletion or infection of files with viruses. If files or data are
accidentally deleted, they will be deleted on all drives. If a
virus attaches itself to a file and starts to replicate this will
also happen on the mirror disk as well.
Interface Type
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An interface is a point of interaction between a
computer and a peripheral. E.g. Between a Hard Disk
and a Desktop computer.
An interface has several functions:
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Temporarily storing data while it is being send between the
processor and peripheral.
Data conversion – analogy to digital and vice versa
Voltage conversion
Protocol conversion - a standard that allows the connection,
communication and data transfer between computers and
peripherals.
Handling of status signals – checking to see if devices are
ready to send and receive data.
USB cables are common connectors for devices.
Data transfer speed
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The data transfer speed is the speed at which
the data can be transferred from one device to
another.
Measured in Megabits or Gigabits per second.
Things that affect data transfer rate:
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Speed of accessing the data on the device e.g. hard
disk spinning around.
Type of interface
Current trends in backing storage
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Solid state storage
devices
Solid state storage devices have
several advantages over magnetic or
optical storage.
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more efficient in terms of their use of
electric power
more robust and harder wearing
since there are no moving parts to
wear down
lighter and smaller than older
storage devices
portable and therefore ideal for
mobile phones, digital cameras,
tablets and ultra-portable
laptops/notebooks
Data transfer rates of 5Gbps.