2.5 - Resilience

Question 1

Define redundancy.

Answer 1

Duplicating parts of the system to maintain uptime.

Prevent hardware, system, and software failure.

Question 2

What is Multipath I/O (Input/ Output)?

Answer 2

Multiple fiber channel interfaces with multiple switches to ensure continued access to data.

Question 3

What is RAID?

Answer 3

Redundant Array of Independent Disks

Multiple drives create redundancy, so if one fails, another can take over.

Question 4

What are the RAID levels?

Answer 4

RAID 0: Striping w/o parity (High speed/ no fault tolerance)
RAID 1: Mirroring (Low speed, 2x space, Fault tolerance)
RAID 5: Striping with Parity

RAID 0+1, RAID 1+ 0, RAID 5 + 1

Question 5

What is a Load Balancer?

Answer 5

Acts as the “traffic cop” sitting in front of your servers and routing client requests across all servers capable of fulfilling those requests across all servers capable of fulfilling those request in a manner that maximizes speed and capacity utilization and ensures that no one server is overworked, which could degrade performance.

Question 6

Define NIC teaming.

Answer 6

Using multiple NICs on a device. Both NICs appear as one. The NICs talk to each other, usually over multicast instead of broadcast. There is a fail over when one of the NICs does not respond.

AKA Load balancing/Fail Over (LBFO).

Question 7

Define Port Aggregation.

Answer 7

A grouping of physical ports acting as a single logical transmission path with other switches which support port aggregation or port channeling.

Question 8

Define UPS (Uninterruptible Power Supply).

Answer 8

A short-term power backup that is good for short blackouts, brownouts, and surges.

Question 9

What are the 3 types of UPS?

Answer 9

1) Offline/ Standby UPS
2) Line-interactive UPS (kicks in during power
shortages)
3) On-line/ Double-conversion UPS (always online and
providing power)

Question 10

What are some features of UPS’s?

Answer 10

Auto shutdown
Battery capacity
Outlets
Phone line suppression

Question 11

What would you use as a long-term power backup?

Answer 11

Generators

Question 12

What are dual-power supplies?

Answer 12

When a device has two power supplies to ensure that when one dies the other will work. Each power supply can handle 100% of the load, but if they are both plugged in, they will split the load.

Often hot-swappable

Question 13

Define Power Distribution Unit (PDU).

Answer 13

A device that provides multiple power outlets and provides monitoring and power control. You can manage power capacity and enable or disable individual outlets.

Question 14

Define Storage area networks (SAN).

Answer 14

A specialized high-performance network of storage devices.

Question 15

What is SAN-to-SAN replication?

Answer 15

The duplication of data from one data center, or SAN, to another data center.

Question 16

What is a SAN snapshot?

Answer 16

A backup that is created of data that is based on a point in time.

Question 17

What are some of the benefits of VM replication?

Answer 17

1) Consistent service offering anywhere in the world
2) Recover from a replicated copy (provides a backup
if needed
3) Efficient copying in that it only replicates the data
that has changed
4) Virtual machine redundancy

Question 18

What are the pros and cons of on premises vs cloud redundancy?

Answer 18

1) Speed
- Local devices can connect faster over a very fast
network
2) Money
- The cloud is almost always cheaper
- on-premises storage is an expensive capital
investment
3) Security
- Local data is private
- Data stored in the cloud requires additional
security controls

Question 19

What is a full file backup?

Answer 19

Backups all of the files and resets the archive bit. EVERYTHING.

Question 20

What is an incremental file backup?

Answer 20

Backups all of the files that have been changed since the last incremental backup and resets their archive bit.

A restoration requires the full backup and all of the incremental backups.

Question 21

What is a differential file backup?

Answer 21

Backups all of the files changed since the last full back up and doesn’t reset the bit.

A restoration requires the full backup and the last differential backup.

Question 22

List out several backup medias.

Answer 22

1) Copy
2) Magnetic tapes
3) Disk
4) Cloud
5) Image
- Capture an exact replica of everything on a
storage drive

Question 23

What are some attributes of magnetic tapes as a backup?

Answer 23

Sequential storage
Easy to ship and store
Slow
100 GB to multiple TB per cartridge

Question 24

What are some attributes of a disk as a backup?

Answer 24

Faster than magnetic tape
Deduplicate and compress

Question 25

What is a Network Attached Storage (NAS)?

Answer 25

A shared storage device that is across the network. Gives file-level access.

Question 26

What is the difference between a NAS and a SAN?

Answer 26

A NAS is a single storage device that serves files over Ethernet and is relatively inexpensive and easy to set up, while a SAN is a tightly coupled network of multiple devices that work with block-based data and is more expensive and complex to set up and manage.

Both require a lot of bandwidth.

Question 27

What is an Offline backup location?

Answer 27

Often an offsite storage for disaster recovery. It can backup to local devices. It must be protect and maintained.

Question 28

What is an Online backup location?

Answer 28

A remote network-connected third-party. It is encrypt and accessible from anywhere. Speed is limited by network bandwidth.

Question 29

What is non-persistence?

Answer 29

System components and services are activated as required using protected information and terminated periodically or at the end of sessions.

Question 30

What is high availability?

Answer 30

An IT system, component, or application can operate at a high level, continuously, without intervention, for a given time period. Infrastructure is configured to deliver quality performance and handle different loads and failures with minimal or zero downtime.

Question 31

What is the Order of Restoration?

Answer 31

Application
Certain components may need to be restored first. Databases should be restored before the application.

Backup
Incremental backups: restore the full backup, then all subsequent incremental backups.
Differential backups: restore the full backup, then the last differential backup

Question 32

What are the benefits of using a diversity of technologies?

Answer 32

Relying on one device, OS, or vendor can lead to shutdowns, but having various different technologies can help to prevent outages and vulnerabilities.

Can have diversity in cryptography and controls (administrative controls, physical controls, technical controls, etc.)