Server replication for rock-solid data availability

By Axelle Drack

Published: October 28, 2024

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

Yes, you're dreading it: the multiplication of requests now makes you vulnerable to breakdowns, and increases the risk of service interruptions. Server replication is essential to ensure continuity.

Find out how server replication works, why you need to use it, and how to go about it the right way. Let's get down to business!

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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);
Changes are detected;
The changes are then passed on to the target server.

💡 The aim is to ensure their 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). They don't just retrieve what the master server sends them.

Passive

With passive replication, only the master server performs the calculations. The final information is then transmitted 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 correct 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 paralyzing the system.

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

Asynchronous

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

→ 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 doesn't guarantee that data is up to date on all servers, but it does improve writing speed while ensuring that you have less than one copy of the data.

Why use replication?

Server-to-server replication aims to :

improve fault tolerance and service interruptions as data volumes increase. 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 different servers to ensure better response times;
provide additional storage space for data backup.

How do you replicate data?

Let's unroll the data replication process.

Step 1: Configure the main server

You'll need to identify and specify which master server is to replicate its data to the target server(s).

Step 2: Configure destination server(s)

Next, you'll need to designate the names of the slave servers and configure them in either 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 wish to replicate:

all server content,
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, you need to define a rule, for example :

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

Get help with data replication

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 running on several of its secure servers, located in France, or on servers of your choice. Worried about losing speed? Its innovative versioning and deduplication system can reduce backup times by up to 80%, so as not to slow down your services. As for security, data is encrypted at source, making it impossible for others to use it once it has been backed up with BeBackup.