Foolproof data availability thanks to server replication

By Axelle Drack

Published: 28 October 2024

Is your company growing fast and having to deal with increasing volumes of data every day? So it's only natural that you should be interested in replicating data on other servers.

Yes, you're dreading it, the increasing load of requests is making you vulnerable to breakdowns and increasing the risk of service interruptions. Server replication is therefore necessary to ensure continuity.

Find out how server replication works, why you need to use it and how to go about doing it properly. Let's get to the point!

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How server replication works

Definition

Data replication is the process of copying data from a master server and storing it on other media, usually one or more servers. These are called target servers, also known as slave or destination servers, and are referred to as server-to-server replication on a network.

It works in three stages:

The master server receives information (data modification, addition or deletion);
The changes are detected;
Then the changes are passed on to the target server.

💡 The aim is to ensure accessibility and availability. In this way, changes made on the master server are automatically, or punctually, reflected on the other servers.

👉 So, in the event of a breakdown on your server, for example, the destination server(s) will be able to take over and continue running your services.

Types of replication

Active

The calculations performed by the source server are also performed by the target server(s). The target server(s) do more than just retrieve what the master server sends them.

Passive

With passive replication, only the master server performs the calculations. The final information is then sent to the other servers.

Synchronous

The target server sends an acknowledgement to confirm that it has received all the data sent. This requires an Ethernet or TCP connection.

👉 In the event of a problem, this ensures that the data is perfectly compliant on the target server. The downside is that processing acknowledgements can overload and slow down the master server. If the server is unavailable, the master server will block writes until the other server(s) are available, potentially paralysing the system.

💡 Our advice: favour synchronous replication if your server hosts critical data.

Asynchronous

The master server sends data without waiting for a return from the target servers.

→ This frees it from a load that could slow down the service. On the other hand, there is no assurance in the event of a problem that all the data present on the target server(s) is indeed the most up-to-date.

💡 Our advice: suitable for small to medium-sized data sets.

Semi-synchronous

Semi-synchronous is a mix between asynchronous and synchronous replication.

Data transmission is validated by the master server once the first destination server has registered it.

👉 This does not guarantee that the data is up to date on all the servers, but it does improve writing speed while ensuring that there is less than one copy of the data.

Why use replication?

The aim of server-to-server replication is to :

improve fault tolerance and service interruptions when the volume of data processed increases. If the main server is unavailable for any reason, the destination server can take over;
guarantee data availability and accessibility;
balance the processing load between the different servers to ensure better response times;
provide additional storage space for backing up data.

How do you replicate data?

Let's take a look at the data replication process.

Step 1: Configure the main server

You will need to identify and specify the master server that is to replicate its data on the target server(s).

Step 2: Configure the destination server(s)

You will then need to designate the names of the slave servers and configure them in passive or active mode. Slave servers must be located on the same network (or domain) as the main server.

Step 3: Configure replication

There are a few parameters to configure before replication can take place.

Choose exactly what you want to replicate, i.e. :

all the contents of the server,
one or more of the server's databases
certain files.

Select the replication frequency, which can be :

periodically,
continuously.

If a conflict is identified, i.e. when the same element has been modified in 2 different places at almost the same time, a rule must be defined, for example :

the most recent modification takes precedence (requires time synchronisation)
define a priority server,
customise.

Get help to replicate your data

What if you called on the services of an expert solution to help you configure and manage the replication of your data and backups? For example, :

BeBackup offers you a solution for replicating your company's backups and VMs, or those of your customers. The solution works with integrated replication mechanisms that run on several of its secure servers, located in France, or on the servers of your choice. Worried about losing speed? Its innovative versioning and deduplication system can reduce backup times by up to 80%, so your services won't be slowed down. As for security, data is encrypted at source, making it impossible for others to use it once it has been backed up with BeBackup.