7.1.5 How physical data storage and recovery systems work, their features, benefits and drawbacks

Question 1

Explain:

What RAID means and what it is

Answer 1

• RAID - Redundant array of independent disks
• Combining of multiple disk drives into a single unit (array)

Question 2

Fill The Blank:

Because disks in RAID work in …………….., RAIDs are more ………….. and ……………. and reduce …….. loss and improve overall performance

Answer 2

Unison, Reliable, Faster, Data

Question 3

Fill The Blank:

The increase in ………… and ……………… from using RAID depend on the ……… used

Answer 3

Speed, Reliability, Type

Question 4

Explain:

RAID 1

Answer 4

• Also called disk mirroring
• Two identical sets of disks and used for redundancy
• If one drive fails, the business can still operate and the broken drive easily replaced with all data copied across from functioning drtive

Question 5

State:

1 advantage and 1 disadvantage of RAID 1

Answer 5

Advantage:
* Increase in read performance due to data being able to be read from either of the two functioning drives

Disadvantage:
* Slightly higher rate latency as the data must be written to both drives in the array

Question 6

Define:

Redundant/Redundancy

Answer 6

Where a system is still able to function regardless of issues that may occur

Question 7

Define:

Read Performance

Answer 7

The time taken to open a file from storage

Question 8

Define:

Rate latency

Answer 8

The amount of time (delay) it takes to send information from one point to the next

Question 9

Explain:

RAID 5

Answer 9

• Contains at least 3 drives (possibly more) with blocks of data being striped across the multiple drives
• Parity bits written across each drive after each sequence of saved data
• Parity checksum is storedo n one drive and used to calculate the value of the parity bits to check whether any data is missing and replace it
• Usually has its own hardware controller

Question 10

State:

1 advantage and 1 disadvantage of RAID 5

Answer 10

Advantage:
* Even more increased performance to RAID 1 because of data striping because data is spread across the drives and can all be read at once

Disadvantage:
* Can only withstand one disk failure and means other data backups should be implemented

Question 11

Explain:

RAID 10

Answer 11

• Combination of disk mirroring and disk striping
• Requires at least 4 drives and a disk controller
• Four disks divided into 2 sets of 2 where each set is RAID 1 for two different sets of data

Question 12

State:

2 advantages and 2 disadvantages of RAID 10

Answer 12

Advantages:
* Data redundancy due to there being a mirrored image of the data
* Increased read/write performance because of data striping
* Rebuild time reduced in the event of a disk failure as long as a mirror image is still available

Disadvantages:
* Does not have parity checking
* If a total failure of one sub-array occurs, the entire system can crash

Question 13

Define:

Data striping

Answer 13

The technique used to store consecutive segments of data (eg: a file) on different physical storage devices

Question 14

Define:

Parity

Answer 14

A technique that checks whether any data has been lost or overwritten when it is moved from one storage place to another or transmitted between computers on a system

Question 15

Explain:

What NAS means and what it is

Answer 15

• NAS - Network Attached Storage
• Storage device that is connected to a network and acts as a central point for the storage, management and access of files

Question 16

Fill The Blank:

As the ……… is connected directly to the network, it can only be accessed by …………………. networked devices or users

Answer 16

NAS, Authorised

Question 17

Fill The Blank:

NAS is configured with data transfer ……………. (DRPs) such as Network File System (NFS) allowing the …………………….. of data between devices

Answer 17

Protocols, Transmission

Question 18

State:

2 advantages of using NAS

Answer 18

• Easy to add additional storage - just have to add additional disk drives
• Data recovery and backup is easier - but should never be only backup option

Question 19

Explain:

What does SAN mean and what it is

Answer 19

• SAN - Storage Area Network
• Network of interconnected storage devices accessible by computers and servers
• Purpose is to store, manage and protect data

Question 20

Fill The Blank:

SAN uses ………….. storage where data is broken down into …………… and stored seperately with each ………… given a unique identifier and a software program …………………….. the requested …………….

Answer 20

Block, Blocks, Block, Reassembles, Block

Question 21

Fill The Blank:

In SAN, once a request is made, the software identifies the blocks based on their unique identifier and …………………. them into one ……… that is then accessible for the user

Answer 21

Reassembled, File

Question 22

Fill The Blank:

Block storage system means data can be accessed more ………….. than a standard file-storage system and can be accessed using different types of …………………. …………………

Answer 22

Quickly, Operating Systems

Question 23

Fill The Blank:

A ………. network is usually connected using ……….-………. cabling which is faster than other forms of cabling and uses a protocol known as fibre channel providing better ……………………

Answer 23

SAN, Fibre-Optic, Performance

Question 24

Fill The Blank:

SANs are ………………… in relation to the technology required and it is also complex to set up, ……………… and …………………….. meaning that there is the additional cost for a skilled ………………….. manager to monitor and maintain the SAN - they are however more easily ……………. by adding hard disks and switches

Answer 24

Expensive, Configure, Maintain, Network, Scalable