For high availability which of the following would be MOST appropriate for fault tolerance?
A.
RAID 0
B.
Clustering
C.
JBOD
D.
Load Balancing
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B.
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Agreed B.
Clustering is very similar to redundant servers and provides fault tolerance. In clustering all servers take part in processing a service simultaneously. A group of servers are logically combined into a cluster and seen as one device, which provides a type of service. If a device fails within a cluster the services continue because the other devices within the cluster continue processing the same services as the failed device. The impact here will be less processing power as the cluster is one less device, however high availability is maintained. The cluster is also providing a load balancing solution as they are all taking some of the processing load, as well as kind of a failover scenario because the other devices continue to process even when one device fails. Overall these redundant devices are maintaining high availability
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Both RAID 0 and JBOD (Just a Bunch Of Disks) are definitely wrong answer. Let us take a closer look between clustering and load balancing.
Clustering has a formal meaning. A cluster is a group of resources that are trying to achieve a common objective, and are aware of one another. Clustering usually involves setting up the resources (servers usually) to exchange details on a particular channel (port) and keep exchanging their states, so a resource’s state is replicated at other places as well. It usually also includes load balancing, wherein, the request is routed to one of the resources in the cluster as per the load balancing policy.
Load balancing can also happen without clustering when we have multiple independent servers that have same setup, but other than that, are unaware of each other. Then, we can use a load balancer to forward requests to either one server or other, but one server does not use the other server’s resources. Also, one resource does not share its state with other resources. Each load balancer basically does following tasks: Continuously check which servers are up. When a new request is received, send it to one of the servers as per the load balancing policy. When a request is received for a user who already has a session, send the user to the same server (This part is important, as otherwise user would keep going between different servers, but not able to really do any work). This part is not required for serving static pages, in that case, there are no user sessions. In short, Load balancing its simple like balancing the request and forwarded to appropriate server for handling the request.
The correct answer is B
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The question does not specify if this is a back-end or a front-end operation.
Both B and D are appropriate answers.
Clustering is good for back-end applications. For example, a SQL Server.
Whereas when it comes to a front-end, Load balancing is much more appropriate/suitable than a cluster. The web servers do not contain the data that changes but only handle client requests to such data. The SQL servers on the other hand contain data that changes (stateful data).
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I choose B too
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We are talking about HIGH AVAILABILITY, and not REDUNDANCY in here.
A- RAID-0 has to do with PERFORMANCE
B- Clustering is the technique of linking many computers together to act like a single computer. This has to do with PERFORMANCE
c-JBOD (which stands for “just a bunch of disks”) generally refers to a collection of hard disks that have not been configured to act as a redundant array of independent disks (RAID) array. This does not provide anything at all.
So the BEST answer to my kind is still “D- Load Balancing.”
Also, we must bear in mind that for the purposes of Security+, there are other similar Load Balancing question where the answer is HIGH AVAILABILITY.
By definition: Load balancing is a key component of HIGHLY-AVAILABLE infrastructures commonly used to improve the performance and reliability of web sites, applications, databases and other services by distributing the workload across multiple servers.
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