RAID Flashcards

1
Q

What are the characteristics of RAID?

A
Redunddancy.
Availability.
Performance.
Capacity.
Economy.
Reliability.
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2
Q

What is redundancy?

A

This refers to backup resourcs that can take action in the case of other resources failing.

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3
Q

What is availability?

A

This refers to components that are always avilable for usage. As they may be needed at all times.

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4
Q

What is performance?

A

This is the rate at which tasks are performed.

For storage devices, it is usually the read and write rates for data in Mb/s.

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5
Q

What is capacity?

A

This is the amount of data tht can be stored?

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6
Q

What is economy?

A

This is the relative cost of a solution based on its benefit.

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7
Q

What is reliability?

A

This is when devices fucntion as intended for a predicited amount of time.

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8
Q

What is RAID?

A

A redundant array of independant disks. (RAID)

It provides a way to store data across multiple drives/disks, for reliability, availability, capacity and redundancy.

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9
Q

When considering RAID solutions, what may be the more economic soltuion?

A

Creating an array of RAID devices, that matches the capacity of a larger RAID device.

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10
Q

What does an operating system recognise a RAID arary as?

A

A singular drive.

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11
Q

What are the four RAID data storage forms?

A

Striping.
Mirroring.
Parity.
Double Parity.

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12
Q

What is striping?

A

A method that enables data to be distribuetd across multiple drives. This provides a significant performance increase.
However, if one drive fails, then all data is lost.

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13
Q

What is mirroring?

A

This method stores duplicate data across multiple drives. This provides a welcome level of redundancy.
The mirror can be recreated by replacing the drive and restoring from a good one.

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14
Q

What is Parity?

A

Ths method provides basic error checking and fault tolerance by storing the checksums seperately.
This enables the resoting of lost data without sacrifcing speed and capacity like mirroring.

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15
Q

What is Double Parity?

A

Double Parity provides fault tolerance for up to two failed drives.

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16
Q

What is the benefit of using hot swappable devices in a RAID structure?

A

Because if a drive fails, that it can be swapped without powering down the array.

17
Q

Do all arrays and RAID types support hot swapping?

A

No.

18
Q

Why is powering down a RAID array bad?

A

Because it may make the data on the RAID unavailabel ot users for an extended period of time. This would impact their ability to work.