Imagine the systems at your business work as a ship. They are all engaged with each other. The systems conjoined in their working and performing tasks. Disasters arise and icebergs hit and suddenly we are in dire need of emergency rescue. The terms fault tolerance, high availability, disaster recovery are quite known in the tech industry. They are emergency rescue services.
Fault tolerance vs high availability has gained popularity to aid in providing shortening downtime. Thereby Fault tolerant Vs high availability helps in keeping the systems working during some component failure.
A few basic differences need to be noted about Fault Tolerant VS high availability. I will cover the topic. Dont worry about that. I will begin though first with a brief definition of what fault tolerance Vs high availability usually entails. The components and types of the two are in discussion.
What is Fault Tolerance?
In cases of system failures of multiple components, fault-tolerant keeps the machine up and running. Basically, under adverse conditions of say supposed hardware or a software error of an application. Fault tolerance will detect the error, and also will make sure the computer runs like every other day.
During times of unreliable hardware of our computers, remember those days? Fault-tolerant VS high availability applications rose to their prominence. Fault-tolerant would make sure in a dual machine. One system would take over the faulty system. Doing so will again ensure the smooth running of the computer.
If youre using no error-allowed computers, fault tolerance will probably come in handy for you.
What are the High Availability and High Availability Cluster?
High availability is used to reduce downtime while not affecting system performance. High availability is designed to cater to the demands of us, the user. In case of a greater degree of damage or hampering of system error, however, you like to term.
The system will start getting affected in its performance when the damage has been competent to hamper the needs of system users. This sensitivity of users is directly proportional to the applications supplied by the system.
High availability clusters are common in places of keeping databases. The various e-commerce websites or transaction processing systems use high availability in their everyday business.
High availability clusters are a group of systems camouflaging into a single working unit. The usual applications of high availability clusters are in the area of backup tasks or failover or load balancing.
To avoid any chances of confusion, lets now delve into a clear distinction between fault tolerance VS high availability. Hopefully, through that, I will be able to provide you with a clear definition and distinction between fault-tolerant VS high availability.
Distinctions of Fault Tolerance VS High Availability
Fault tolerance VS high availability though they operate in different methods. Fault Tolerant VS high availability performs the same task of making sure the system runs smoothly in cases of errors and failures.
The difference that needs to be addressed in the case of fault tolerance VS high availability.
- Fault Tolerance in the working process uses specific hardware for detecting hardware failures. Thereafter makes the switch to a redundant component of the hardware present on the system. The redundant component of the hardware used not being processed makes the entire operation costly. The transformation and service though is very smooth as expected.
- Software failures are usually the cheap factor working in causing downtime. Fault tolerance works only for hardware mechanisms and fails to detect software errors.
- High availability works as a form of replicated systems. As I talked about the camouflaging of several systems working together. The concept of systems-sharing components as a form of collaboration is not applicable. The system-shared resources are seen as always replicated.
- High availability works in joining the software with the hardware to perform the task of downtime minimization. High availability restores essentials in cases of application failures or system failures or component failures for that matter. The whole process is to be completed and services are to be restored. This usually takes less than a minute.
So to draw the basic difference between fault tolerant VS high availability. It should be summarized as follows. Fault tolerance runs smooth but is costlier to use. High availability is cheaper to use but there will be run-ins with service interruption disturbances.
Which one are you leaning towards now between fault tolerant VS high availability for your need?
The Measuring Index
The measuring Index is a useful denominator to understand better fault tolerance Vs high availability. Lets start with fault tolerance first.
Fault Tolerance: 1) System Reliability
2) System testability
3) System availability
High Availability: A specific formula is designed to measure index high availability.
%Availability = (Total Elapsed Time- Sum of Inoperative Times)/Total Elapsed Time.
Elapsed Time=Operating Time + Downtime.
Required Infrastructure System
All these formulas and calculations become unnecessary and faux without the right infrastructure in place. What good is writing about fault-tolerant VS high availability? If we dont have the infrastructure, to begin with.
I will start here with high availability first. High Availability for the application to work there needs to be complete replication of system components. Once done, high availability will provide smooth services to outages and other failure errors.
You might have gauged by now in our long discussion of fault-tolerant VS high availability. That fault tolerance works in a much more complex manner. Fault Tolerance acts for processing traffic. All the while it replicates information.
This replication of data from both the hardware and software is rather an elongated process. This process therefore takes time and is difficult.
At last, we must discuss the good and the bad of fault tolerance VS high availability.
The Good and the Bad of Fault Tolerant VS High Availability
Talking about the pros of high availability, one must first begin with the,
- Cost friendly: High availability is easy to use and maintain owing to the simple mechanisms of the application.
- Easily Adaptable: High availability the entire process design of the system is rather simplified.
- Load Balance: The multiple environments ensure the traffic is split over, therefore the traffic combines in a failed attempt.
The cons of high availability are few and far between but needs must be discussed.
- Disruption of Service: The downtime of high availability will consume several seconds now and then.
- Data Loss: Systems using high availability may incur data loss on some rare occasions. This is largely due to a narrow gap of an outage. Usually, in such cases, the major damage is data loss.
The good bits about data tolerance are as follows.
- No Interruption: There are absolutely no such occasions of interruptions with an increase in user reliability of the application. Fault tolerance also provides the power to the user to intervene in different situations in case leading to any delay.
- Zero Data Loss: Fault Tolerance always ensures there is no data loss. This is a key underlying component. The no data loss factor often tips scales in favor of fault tolerance in the fault-tolerant VS high availability debate.
Lets now talk about the bad bits of fault tolerance.
- Complexity: Complexity of the fault tolerance can at times turn its boon into its self-serving problem. The complex design results in system failures. These system failures intervene in the working of the system.
- Not at all Cost Friendly: The complex design of the system of fault tolerance is directly proportional to the operational cost. There are a multitude of pieces that when combined make a good hole in the pocket.
High Availability VS Disaster Recovery
Different from the previous fault tolerant vs high availability, disaster recovery is different. Disaster Recovery is commonly considered the advanced version of high availability.
Disaster Recovery ranges anything from backup to advanced functions. These usually depend on the factors of RTO and RPO. RTO is the Recovery Time Objective and RPO is Recovery Point Objective.
RTO and RPO combine in constant active implementation of data being replicated. The primary and the recovery systems are the two bases of data replication. RTO and RPO keep a readymade failover system or almost ready in some cases. Disaster recovery jumps in therefore whenever disaster strikes the systems.
The opinion polls on high availability vs disaster recovery have certainly been in disaster recoverys favor. High availability works on a running system. Disaster recovery comes into play when the system has failed.
This has to be the primary difference between high availability VS disaster recovery. Though both high availability and disaster recovery work in keeping the system operational.
All that You Needed to Know
I have tried to provide the basics of Fault-tolerant VS high availability. The more advanced days of high availability vs disaster recovery. The RTO and RPOs of disaster recovery perform backups of application servers and databases. This makes disaster recovery so used an application these days.
The cost is always requiring calculation. There must be a balance between the costs and whether the data recovered is worth that cost.
Frequently Asked Questions
Q1. What is the difference between unavailable and high availability?
The difference between unavailable and high availability is pretty self-explanatory. Unavailability is when the system has failed and is no longer operating. High availability looks after the continuous working of the system at all times for a good length of time.
Q2. What hardware-based solutions are measures for fault tolerance?
The hardware-based solutions for fault tolerance are:
- Load Balancing