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Which RAID implementation uses two disks in a mirrored configuration?
RAID 1 uses two disks in a mirrored configuration.
Which RAID implementation employs disk striping with parity and requiresa minimum of three disks?
RAID 5 is disk striping with parity, requiring three disks at a minimum
What technology involves grouping servers for the purposes of fault tolerance and load balancing?
Server clustering involves grouping servers for the purposes of fault tolerance and load balancing.
What protocol enables multiple hosts on the same network to share a set of IP addresses?
Common Address Redundancy Protocol (CARP).
What is fault tolerance?
For computers, fault tolerance refers to the capability of the computer system or network to provide continued data availability if hardware failure occurs.
On a computer system what requires the most redundancy?
What is hard disk fault tolerance?
A backup plan which allows for the services provided by the hard disk to continue.
Disadvantage of RAID 0?
No fault tolerance. One disk dies all data is lost.
Advantages of RAID 0?
Increased read and write performance. RAID 0 can be implemented with two or more disks.
How many disk required for RAID 0?
2 or more.
What is RAID 1?
Advantages of RAID 1?
Provides fault tolerance. Can also be used with separate disk controllers, reducing the single point of failure. This is called disk duplexing.
Cheap b/c you are using two smaller disks
No new hardware, implemented by most OSs
Load balancing over disks.
Disdvantages of RAID 1?
RAID 1 has 50% overhead and suffers from poor write performance.
RAID 1 is incapable of including boot or system partions.
Disks required for RAID 1?
What is RAID 5?
Striping with distributed parity.
Advantages of RAID 5?
Can recover from a single disk failure. Increased read performance over a poor write single disk. Disks can be added to the array to increase storage capacity.
Disadvantages of RAID 5?
May slow down the network during regeneration time, and performance may suffer.
How many disks required for RAID 5?
Minimum of 3.
Explain RAID 5 parity?
RAID 5 includes parity information in the striping, which provides fault tolerance.This parity information can re-create the data if a failure occurs. RAID5 requires a minimum of three disks, with the equivalent of a single disk used for the parity information. This means that if you have three 1 TB disks you have 2 TB of storage spae, with the other 1 TB used for parity.
What is RAID 10?
One such strategy is RAID 10, which combines RAID levels 1 and 0. In this configuration, four disks are required. As you might expect, the configuration consists of a mirrored stripe set. To some extent, RAID 10 takes advantage of the performance capability of a stripe set while offering the fault tolerance of a mirrored solution. In addition to the benefits of each, though, RAID 10 inherits the shortcomings of each strategy. In this case, the high overhead and decreased write performance are the disadvantages.
Advantages of RAID 10?
Increased performance with striping. Offers mirrored fault tolerance.
Disadvantages of RAID 10?
High overhead as with mirroring.
How many disks required for RAID 10?
What are standby servers?
Standby servers are a fault-tolerance measure in which a second server is identically configured to the first one. The second server can be stored remotely or locally and set up in a failover configuration. In a failover configuration, the sec-ondary server connects to the primary and is ready to take over the server functions at a moment’s notice. If the secondary server detects that the primary has failed, it automatically cuts in. Network users will not notice the transition, because little or no disruption in data availability occurs.
What are heartbeats?
Notifications sent by the primary server to the secondary server to let it know it is still functioning.
Servers grouped together for fault tolerance and load balancing.
Advantages of server cluster or server farm?
. Increased performance: More servers equals more processing power. The servers in a cluster can provide levels of performance beyond the scope of a single system by combining resources and processing power.
. Load balancing: Rather than having individual servers perform specific roles, a cluster can perform a number of roles, assigning the appropriate resources in the best places. This approach maximizes the power of the systems by allocating tasks based on which server in the cluster can best service the request.
. Failover: Because the servers in the cluster are in constant contact with each other, they can detect and cope with the failure of an individual system. How transparent the failover is to users depends on the clustering software, the type of failure, and the capability of the application software used to cope with the failure.
. Scalability: The capability to add servers to the cluster offers a degree of scalability simply not possible in a single-server scenario. It is worth mentioning, though, that clustering on PC platforms is still in its relative infancy, and the number of machines that can be included in a cluster is still limited.
Groups of NICs are configured to act as a single unit through the use of special software.
Benefits of adapter teaming?
Adapter fault tolerance: One card is primary the others are secondary. When primary fails a secondary takes place. When failed primary is replaced it resumes its position as primary card.
Adaptor load balancing: The software controling the network adaptors will distribute the work. This enables a more responsive server because one card is not responsible all of them are.
Link Aggregation: Bandwidth with multiple cards is aggregated. The cards and the switch have to support it.
What is Common Address Protocol (CARP)?
Common Address Redundancy Protocol (CARP) is a protocol that enables multiple hosts on the same network to share a set of IP addresses and thus provides failover redundancy. It is commonly used with routers and firewalls and can provide load balancing.
What are the hosts within the redundant group known as?
Group of redundancy. CARP requires a minimum of one common virtual host ID and a set of virtual host IP addresses (one for each machine taking part in the group).
Who owns CARP?
It is Open Source.
Why use a UPS?
Data availability: A UPS will ensure access if a power failure occurs.
Protection from data loss: Fluctuations in power or a sudden power down can damage the data on the server system. In addition, many servers take full advantage of caching, and a sudden loss of power could cause the loss of all information held in cache.
Protection from hardware damage: Constant power fluctuations or sudden power-downs can damage hardware components within a computer. Damaged hardware can lead to reduced data availability while the hardware is repaired.
UPS and Power Threats
. Blackout: A total failure of the power supplied to the server.
. Spike: A short (usually less than 1 second) but intense increase in voltage. Spikes can do irreparable damage to any kind of equipment, especially computers.
. Surge: Compared to a spike, a surge is a considerably longer (sometimes many seconds) but usually less intense increase in power. Surges can also damage your computer equipment.
. Sag: A short-term voltage drop (the opposite of a spike). This type of voltage drop can cause a server to reboot.
. Brownout: A drop in voltage that usually lasts more than a few minutes.
Which of the following is a common phrase used for server clustering?
In the server room you find a box with five 2TB hard disks. If you were to implement a RAID 5 solution using all five disks, how much storage space would you
have for the actual data?
❍ A. 10TGB
❍ B. 8TB
❍ C. 4TB
❍ D. 6TB
With CARP, what are the hosts within a redundant group known as?
❍ A. Range of possibles
❍ B. Redundancy scope
❍ C. Redundancy pool
❍ D. Group of redundancy
Which of the following RAID levels offers the greatest read-and-write performance?
Which of the following power-related problems is associated with a short-term voltage drop?
❍ A. Surge
❍ B. Brownout
❍ C. Sag
❍ D. Spike
As a network administrator, you have been asked to implement a RAID solution that offers high performance. Fault tolerance is not a concern. Which RAID level
are you likely to use?
❍ A. RAID0
❍ B. RAID1
❍ C. RAID2
❍ D. RAID5
❍ E. RAID10