Lesson 11 Chapter 4 - RAID

Question 1

In summary, what is an array? (RAID)

Answer 1

An array is several drives working as a unit (to protect data or increase speed)

Question 2

What are RAID levels?

Answer 2

The different RAID setups (specific purposes)

Question 3

What does RAID 0 – Disk Striping do?

Answer 3

It spreads out the data to be written across 2 or more drives

(For example, with 2 drives only half is written/read on each drive)

Question 4

What does RAID 1 – Disk Mirroring/Duplexing do?

Answer 4

The data is duplicated – the same data is written to both drives simultaneously (mirrored)

Question 5

What is RAID 5?

Answer 5

Disk Striping with Distributed Parity

Question 6

What does level 5 RAID – Disk Striping with Distributed Parity do? (3 steps)

spreads out, the parity bit, distributed parity

Answer 6

It:
- spreads out the data and splits the bits and parity bit to different drives (3 drives, 3 separate bits)
- the parity bit (0 for even, 1 for odd) depends on the sum of the value of the bits that are spread out (1 1 or 0 0 is even, 1 0 or 0 1 is odd)
- distributed parity comes in and alternates the order/drives it writes the bits and parity bit to

Question 7

What is the parity bit that is written for RAID 5 if the sum of the bit value is even or odd? (2)

Answer 7

0 = even
1 = odd

Question 8

How does RAID 5 – Disk Striping with Distributed Parity, protect against hardware failure?

Answer 8

The RAID controller can deduce what the value on the failed+replaced disk was from reading what bit and parity bit is stored on the other working drives

(It has enough of the equation that it can rewrite to the new disk to rebuild its content)

Question 9

What are the 4 common RAID level numbers and their name/function?

DS, DM/D, DSwDP, NSP

Answer 9

1. RAID 0 – Disk Striping [spread, speed and size]
2. RAID 1 – Disk Mirroring/Duplexing [mirror protect]
3. RAID 5 – Disk Striping with Distributed Parity [spread protect]
4. RAID 10 – Nested, Striped Pairs [spread, 2 mirror speed protect]

Question 10

Of all the RAID levels which one has an advantage over RAID 5 or 6? What is the advantage? (2)

Answer 10

RAID 10 has an advantage over 5 and 6, its performance is increased because the controller doesn’t have to calculate the parity bits

Question 11

How many hard drives does each of the 4 common RAID levels require at a minimum?

Answer 11

1. RAID 0 – requires 2
2. RAID 1 – requires 2
3. RAID 5 – requires 3
4. RAID 10 – requires 4

Question 12

How many failures can each level RAID withstand and remain functional? (4)

Answer 12

can withstand:
1. RAID 0 - 0 failures
2. RAID 1 - 1 failure
3. RAID 5 - 1 failure
4. RAID 10 - Up to 2 failures

Question 13

With a RAID 5 array, the amount of storage you get is always ___ ___ drive than the total drives you have

Answer 13

one less

Example: 3 5TB drives, your total storage is actually 10TB

Question 14

What are 2 ways a hardware RAID can be accessed by its RAID controller? [Controller installed]

Answer 14

1. RAID controller is built into the motherboard and managed via firmware interface
2. Can be a separate add-on expansion card

Question 15

How is software RAID configured?

Answer 15

a utility in the OS

(Disk Management)

Question 16

Why shouldn’t you mix HHDs with SSDs in the same hardware RAIDs?

Answer 16

The speed will be limited to the HDDs

Question 17

When should you use hardware RAID versus software RAID? (2)

Answer 17

hardware: specifically for performance – speed and efficiency
software: when price>performance, or small simple RAID for data protection (OS in charge of RAID = slowdowns)

Question 18

Since hardware RAID uses an intelligent controller, what are the two types of controllers it uses to handle the functions?

Answer 18

1. PATA controller
2. SATA controller

Question 19

What’s the difference between hardware RAID controllers and regular controllers?

Answer 19

RAID controllers are intelligent and have chips with their own processor and memory

Question 20

Almost all hardware RAID solutions provide __ ____

Cheetos

Answer 20

hot swapping (replace a bad drive without disturbing OS)

Question 21

How do you access hardware-based RAIDs?

a special
barry

Answer 21

a special configuration utility in flash ROM that’s accessed after CMOS but before OS loads

Question 22

What does JBOD stand for?

Answer 22

Just a Bunch of Disks

Question 23

What does JBOD allow you to do? [hardware]

Answer 23

JBOD arrays allow you to physically connect multiple hard drives of different capacities and combine them to use as a single-volume

Question 24

Common software RAID is the built-in RAID software that comes with what 3 Windows versions?

Answer 24

1. Professional
2. Business
3. Ultimate

Question 25

The Disk Management utility in desktop versions of Windows 10 and 11 can do what two RAID levels?

Answer 25

RAID 0 and RAID 1

Question 26

Server editions of Windows can configure drives for what 3 RAID levels?

Answer 26

1. RAID 0
2. RAID 1
3. RAID 5

Question 27

What does the Home edition of Windows support with RAID?

Answer 27

Limited support for RAID but can use the Storage Spaces utility that lets you logically combine the storage of multiple drives into a single logical drive

Question 28

What’s the difference between JBOD and the Storage Spaces utility?

Answer 28

JBOD (like a lot of RAID) happens at the hardware level. You connect the physical drives of different capacities to combine them into a single logical drive/volume.

Storage Spaces is a software utility

Question 29

What’s a benefit you have when you have to troubleshoot a problem with a RAID array [hardware]?

Answer 29

There is usually a RAID configuration utility that tells you which drive is causing a problem so you can replace it

Question 30

What are 3 issues that can arise with RAID arrays?

Answer 30

1. RAID stops working
2. Drives not recognized
3. Entire RAID missing

Question 31

What are the 3 places to look when you notice slow performance from a suspected failing drive?

Answer 31

1. Device Manager
2. RAID controller utility (hardware RAID)
3. Disk Management (Windows-based software RAID)

Question 32

Some drive failures will cause 1 of 2 things:

Answer 32

1. Computer crashes (BSoD)
2. Error won’t show up until reboot

Question 33

How do you troubleshoot hardware RAID error “Drive not recognized”? (2)

Answer 33

1. Drives are powered?
2. Connected to the proper connection? (special RAID connectors for motherboards with onboard RAID?)

Question 34

How do you troubleshoot an entire RAID array that’s missing?

Answer 34

If it doesn’t show up in the configuration utility (if it works, it should), then either multiple drives are dead or there’s a faulty controller (replace it)