An Overview of Failover – What Is It and What’s the Special

What Is Failover?

What is failover? Failover can be divided into different types. When you are in trouble, an advance failover plan can do you a favor.

Failover is a backup mode of operation in which the functions of system components, such as processors, servers, networks, or databases, are transferred to secondary system components when the primary component fails due to failure or scheduled shutdown.

Failover is an essential part of an emergency mission system that must be used frequently in order to make the system more fail-tolerant.

This program consists of automatically offloading tasks to standby system components so that the program is as trouble-free as possible for the end-user.

Failover can be applied to many aspects of a system.

Within a personal computer, for example, failover may be a mechanism to protect a failing processor.

Within a network, failover can be applied to many network components or system components, such as connection paths, storage devices, or web servers.

Initially, stored data is connected to the server in a very basic configuration – point-to-point or cross-connection.

In this environment, the failure of a single server often leaves a large number of users without access to data until that server is back online.

Storage networks use many paths between servers and systems and each path consists of a complete configuration that includes all the relevant components. A failed path may be due to the failure of some individual components in the path.

Multiple connected paths, each with redundant components, often help ensure that the line remains viable even if one (or more) paths fail.

Failover is the ability to maintain normal functions despite an inevitable failure due to a device problem.

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Failover has different types that can be applied in emergency plan, but in most cases, the business will rely more on automatic failover, which is also the most used in failover. So this article will give you an introduction to automatic failover first.

What Is Automatic Failover?

Automatic failover is a best practice for systems that experience damage or lose vital connectivity during various scenarios, such as storms and natural disasters.

Businesses may use automatic failover systems to protect against data loss in such situations, which are often referred to as disaster recovery plans or emergency planning.

The alternative is a passive system where the process happens manually. Most failover processes operate automatically to reduce downtime.

There is another similar definition – switchover. We can give a brief introduction to automatic failover vs switchover.

Automatic Failover vs Switchover

First of all, what is the switchover?

Switchover is the manual switch from one system to a redundant or standby computer server, system, or network upon the failure or abnormal termination of the previously active server, system, or network, or to perform system maintenance, such as installing patches, and upgrading software or hardware.

https://en.wikipedia.org/wiki/Switchover

You can tell their greatest difference from their definitions. Switchover requires manual operation; automatic failover doesn’t need any human intervention.

If your automatic failover is not available, you can try switchover. Of course, manual failover is also allowed.

Furthermore, the switchover is suitable for complex databases, while failover is suitable for less complex databases.

What Is Failover Cluster?

The failover cluster, composed of multiple computers, is a high availability infrastructure layer. Each computer is equivalent to a redundant node in which the entire cluster system allows a part of the node to go offline, fail or damage without affecting the normal operation of the entire system.

The process by which a server takes over a failed server is often called “failover”.

The failover cluster must be deployed based on the domain-based management mode, with a special mechanism to monitor the health of every node. The standby server will check whether the active server is in normal functioning or not.

Before activating the standby server, the failover cluster must make sure the active server is out of operation.

Failover clusters can be deployed in Windows Server 2003, Windows Server 2008, and Windows 2012 Server operating systems.

How Does Failover Works?

All forms of failover need the support of a given availability replica. The possible failover modes depend on the availability mode of the replica. There are two major replicas – synchronous-commit replicas and asynchronous-commit replicas.

Synchronous-commit Replicas

Only the manual forced failover mode is supported by these replicas.

Synchronous-commit mode emphasizes high availability over performance, at the cost of increased transaction latency. Under synchronous-commit mode, transactions wait to send the transaction confirmation to the client until the secondary replica has hardened the log to disk.

Asynchronous-commit Replicas

Two settings-automatic or manual failover modes are supported by these replicas.

To prevent data loss, automatic failover and planned failover require that the failover target be a synchronous-commit secondary replica with a healthy synchronization state, which means every secondary database on the failover target is synchronized with its corresponding primary database.

Different Types of Failover

Automatic Failover

Automatic failover is supported only when the current primary and one secondary replica are both configured with failover mode set to automatic and the secondary replica is currently synchronized.

Planned Manual Failover

It is created by a database administrator, typically, for administrative purposes.

A planned manual failover is supported only if both the primary replica and secondary replica are configured for synchronous-commit mode, and both the primary replica and secondary replica are currently synchronized.

This failover can prevent data loss in a better way.

Forced Failover

It can be initiated by a database administrator when no secondary replica is synchronized with the primary replica or the primary replica is not running and no secondary replica is failover ready.

It is the only one that can be supported by synchronous-commit replicas but this failover just comes with possible data loss.

Automatic Failover Set

An automatic failover set takes effect only if the secondary replica is currently synchronized with the primary replica.

Synchronous-Commit Failover Set

A synchronous-commit failover set takes effect only if the secondary replicas are configured for manual failover mode and at least one secondary replica is currently synchronized with the primary replica.

Entire Failover Set

When there is no secondary replica synchronized with the primary replica, the entire failover set will happen.

Although we have introduced multiple types of failover, the major is three – automatic failover, manual failover, and forced failover. This is an overview of them.

A Sum-up of Failover

Automatic failover is only supported by synchronous-commit mode with automatic-failover mode.

Manual failover is supported by two modes – synchronous-commit mode with manual-failover mode and synchronous-commit mode with automatic-failover mode.

Forced failover is supported by three modes – asynchronous-commit mode, synchronous-commit mode with manual-failover mode, and synchronous-commit mode with automatic-failover mode.

Why Is Failover So Important?

As we mentioned, failover is more commonly used in companies for a large number of data must stay secured and undamaged. It is also suitable for personal use but most of us just ignore its great function in our life.

There are multiple reasons to apply failover:

1. It can minimize your loss and save your money. When system failure, damaged devices, or other terrible things happen, you may face a great data loss and the potential cost of downtime, the cost of which definitely goes far more than the failover.

2. When computer failure happens, automatic failover will start, which will leave you enough time to troubleshoot the hidden reason and give you a buffer to save your data.

3. Greatly eliminate downtime and maintain great customer service as if no wrongs happen.

In this way, many companies will use a failover plan to mitigate risks.

Is Failover a Backup?

The answer is no. Failover and backup are two different processes. Some people may think failover has the same function and purpose as a backup and then think of them as one thing.

Although they are designed to prevent data loss in some aspects, failover can be regarded as an emergency plan in which your learning management system can be protected from downtime; backup is for saving your data in a safe place for recovery after a disaster.

Failover has its advantage in protecting your data but that doesn’t mean you have no use for backing up data on a regular basis. During the failover plan, you are still at the risk of losing data until the issue is fixed.

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A Choice to Protect Your Data

To better avoid risks, it is recommended to back up your data at a scheduled time. When your failover loses efficacy, you will be thankful for your advance backup plan. Your system data will be stored in a safe destination and the only thing you need to do is recover it.

Considering the situation, a reliable backup expert – MiniTool ShadowMaker shows up to become your right hand. It boasts its reputable and mature backup experience and wins people’s praise.

First of all, you need to download and install the program to get a free trial version for 30 days.

Step 1: Open the MiniTool ShadowMaker and click Keep Trial on the top right corner.

Step 2: Go to the Backup tab. The system has been set by default, so you don’t need to change it. You can also select your other backup sources when you need them, including disk and partitions, and folders and files.

Step 3: Go to the Destination part where you can see four options containing the Administrator account folder, Libraries, Computer, and Shared. Then choose your destination path. And then click OK to save your changes.

Step 4: Click the Back up Now option to start the process immediately or the Back up Later option to delay the backup. The delayed backup task is on the Manage page.

We have stressed how important it is to have a good habit of backup. You don’t need to worry about forgetting that because MiniTool ShadowMaker has the Schedule option to resolve this issue.

MiniTool ShadowMaker provides some advanced backup options such as Image Creation Mode, File Size, Compression, etc. Besides, you are allowed to set a password for your backup to increase its security.

This article mainly talks about failover. What is it? How does it work? And multiple types of failover will be introduced. If you are interested, you can share it on your Twitter.Click to Tweet

Bottom Line:

Whether for a business or an individual, a sudden system crash will be a big trouble to handle. It has become a long-standing topic surrounding people’s life to discuss how to protect your data integrity. Failover can be your remedy but backing up your data on a regular basis is more important.

If you have encountered any issues when using MiniTool ShadowMaker, you can leave a message in the following comment zone and we will reply as soon as possible. If you need any help when using MiniTool software, you may contact us via [email protected].

Failover FAQ: