7.1.5 How physical data storage and recovery systems work, their features, benefits and drawbacks Flashcards
Explain:
What RAID means and what it is
- RAID - Redundant array of independent disks
- Combining of multiple disk drives into a single unit (array)
Fill The Blank:
Because disks in RAID work in …………….., RAIDs are more ………….. and ……………. and reduce …….. loss and improve overall performance
Unison, Reliable, Faster, Data
Fill The Blank:
The increase in ………… and ……………… from using RAID depend on the ……… used
Speed, Reliability, Type
Explain:
RAID 1
- 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
State:
1 advantage and 1 disadvantage of RAID 1
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
Define:
Redundant/Redundancy
Where a system is still able to function regardless of issues that may occur
Define:
Read Performance
The time taken to open a file from storage
Define:
Rate latency
The amount of time (delay) it takes to send information from one point to the next
Explain:
RAID 5
- 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
State:
1 advantage and 1 disadvantage of RAID 5
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
Explain:
RAID 10
- 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
State:
2 advantages and 2 disadvantages of RAID 10
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
Define:
Data striping
The technique used to store consecutive segments of data (eg: a file) on different physical storage devices
Define:
Parity
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
Explain:
What NAS means and what it is
- 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
Fill The Blank:
As the ……… is connected directly to the network, it can only be accessed by …………………. networked devices or users
NAS, Authorised
Fill The Blank:
NAS is configured with data transfer ……………. (DRPs) such as Network File System (NFS) allowing the …………………….. of data between devices
Protocols, Transmission
State:
2 advantages of using NAS
- 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
Explain:
What does SAN mean and what it is
- SAN - Storage Area Network
- Network of interconnected storage devices accessible by computers and servers
- Purpose is to store, manage and protect data
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 …………….
Block, Blocks, Block, Reassembles, Block
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
Reassembled, File
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 …………………. …………………
Quickly, Operating Systems
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 ……………………
SAN, Fibre-Optic, Performance
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
Expensive, Configure, Maintain, Network, Scalable
