Redundancy, Fault Tolerance, and High Availability 3.8

Question 1

Distributive Allocation

Answer 1

The bad guys are looking for your data. Most of the time it will be in a data center. One of the best ways to protect things are by spreading your critical assets, data and other components out. If they find one thing, they will still need to find the others. It’s also allows you to add more barriers between different places.

Question 2

Redundancy and Fault Tolerance

Answer 2

One primary goal of a security system is to maintain 100% uptime. This applies to both software and hardware. Have multiple servers available and backup equipment available.

Question 3

Redundant Array of Independent Disks (RAID)

Answer 3

Multiple physical drives in a server, if one drive fails, you have the others. There are different levels of RAID. Each organization will need to identify what level of RAID is the right fit for them.

Question 4

Uninterruptible Power Supplied (UPS)

Answer 4

Extra power supplies in case of power supply failure.

Question 5

Data Striping

Answer 5

Data striping is the technique of segmenting logically sequential data, such as a file, so that consecutive segments are stored on different physical storage devices.

Question 6

RAID 0 (Striped Disk)

Answer 6

Spreads data out across multiple disks. Improves retrieval speed. Does not improve reliability. Losing one drive loses all the drives.

Minimum Number of Drives: 2
Striping: Yes
Mirroring: No
Parity Data: No

Question 7

RAID 1 (Mirrored Disk)

Answer 7

Copies data from primary disk onto two or more disks. Improves reliability and can also improve retrieval speed. Expensive compared to other RAID methods.

Minimum Number of Drives: 2
Striping: No
Mirroring: Yes
Parity Data: No

Question 8

RAID 2 (bit-level error-correcting code)

Answer 8

Not often used. Stripes data across drives at bit level instead of block level. Designed to recover loss of single disk data through error correcting techniques.

Minimum Number of Drives: 3
Striping: Yes
Mirroring: No
Parity Data: Yes (uses Hamming code) (obsolete)

Question 9

RAID 3 (byte-striped with error check)

Answer 9

Data spread across multiple disks at byte level. One disk dedicated to parity bits. (checks if data sent is correct).

Minimum Number of Drives: 3
Striping: Yes
Mirroring: No
Parity Data: Yes

Question 10

RAID 4 (dedicated parity drive)

Answer 10

Stripes data like RAID 3 but in larger stripes. Slower.

Minimum Number of Drives: 3
Striping: Yes
Mirroring: No
Parity Data: Yes

Question 11

RAID 5 (block-striped with error check)

Answer 11

Stripes data at block level and spread parity across multiple drives. Provides reliability and increased performance. Requires minimum of 3 drives.

Minimum Number of Drives: 3
Striping: Yes
Mirroring: No
Parity Data: Yes

Question 12

RAID 6 (block-striped with error check)+

Answer 12

Same as RAID 5 but uses two parity blocks.

Minimum Number of Drives: 4
Striping: Yes
Mirroring: No
Parity Data: Yes