How Does Managed Database Replication Work & When Does Your Website Need It?

Nothing is more important or impactful to the daily website operation than its database. Afterall, it’s where all the most important data is stored. Whether it is general MySQL, Percona MySQL, MariaDB, PostgreSQL, MongoDB, Microsoft SQL, or even micro-databases like SQLite, your database needs to be agile, accessible, secure, and above all else resilient.

In this modern age, data-loss cripples and/or bankrupts even the largest of businesses in every industry. Making sure your database ticks off these checkboxes is a critical necessity for the future growth and sustainability of your website/application. However, how does one achieve database resilience? The answer to this question is Database Replication.

Similar to our previous article on managed file replication, we’ll walk you through the basics of Database Replication and explain the benefits to showcase why we feature it in some of our enterprise hosting packages.

What is Database Replication?

The practice of synchronizing databases between multiple separate database servers. Database Replication occurs when two or more database servers are configured into a Master/Slave or Master/Master configuration. All changes made to the Master nodes are synced with all other nodes in that database replication cluster. All your most common database software typically have a replication feature that governs and replicates the necessary changes.

There are two distinct flavors of Database Replication used in today’s enterprise hosting industry. The difference in function and complexity is distinct, but both Read-Slaved and Multi-Master replication solutions are available to solve your specific needs.

What Is Read-Slaved Database Replication?

The more common of the two types as it is much easier to build and maintain. A one-way approach to database replication is known as Read-Slaved. This means there is a single master node in the replication cluster that handles all write-based traffic. While any number of additional slave nodes can be added for handling the read-based requests.

Most sites have a heavy ratio of databases reads to writes: 10:1, 20:1, or even as high as 100:1. It’s clear that write-based traffic can be isolated to it’s own master node while multiple slaves make up the bulk of handling read requests.

This type of replication requires that your website/application can divide its read traffic to target a separate database server while reads are sent to be both the master and any slaves. There is a non-trivial amount of development work involved with making an software work in these types of cluster.

What Is Multi-Master Database Replication?

A more complicated solution than Read-Slaving is Multi-Master. In these clusters there are two or more master servers which share the workload evenly. Many database products on the market support read-slaving, but not all of them can successfully service in a multi-master model.

Multi-Master setups are typically needed when your application read:write ratio is shifted in the other direction: 1:10, 1:20, and so on. Write focused applications will need to work out the logistics of writing changes to multiple master servers without falling into a race condition when two operations on the same table and/or row occurs.

What Is Managed Database Replication?

The key difference between Database Replication and Managed Database Replication is simple. Database Replication defines the process of replicating data across multiple database servers. Managed Database Replication is an enterprise tier hosting service provided by SirsteveHQ’s top tier enterprise packages. Our everyday heroes setup, configure, and maintain your database replication cluster so you don’t have to. Your replication cluster is monitored 24x7x365 and our heroes automatically respond and act to correct any problems detected within the replication system. Managed Database Replication brings peace of mind to website owner’s who can count on SirsteveHQ to ensure the health and well being of their most important data.

When Does My Website Need Database Replication?

The answer is a rather simple one, as soon as it’s fiscally viable for your business. Database Replication is essential for websites/applications at all levels where user-data is stored in a database. It’s not possible to simply copy your database files from one location to another and expect them to work without issue. In fast, doing so can lead to data-loss or corruption, which is arguably worse depending on the scenario.

The following is a list of key benefits garnered by deploying and adequate Database Replication setup.

Benefit #1: Performance

The ability to split your database workload across multiple hosts is an innate boost to performance. The additional cluster members provide a break for the others when one has reached its natural performance constraints on a single host.

The Bank Teller Analogy – You can think of database replication like your local bank branch office. Have you ever been stuck in one of those rope maze lines behind several other individuals who are all eagerly awaiting in line for their turn at the teller. You represent your visitors requests in this analogy and it’s no picnic being 10th in line while one teller handles all the workload. Now imagine the relief everyone in line feels when a second or third bank teller opens their windows. The wait time for getting your request fielded immediately halves and the line is no longer held up by one person’s very long request at the teller.

Benefit #2: Database Resilience

A secondary node in a Database Replication cluster can service to protect you from hardware failure scenarios by having a real-time copy of your data. No longer will the your website be susceptible to many downtime events resulting from your database server crashing. One cluster member can undergo any sort of hardware maintenance while its counterpart(s) take care of servicing the business.

Benefit #3: Always Online

Database Replication clusters are the means by which your database can obtain the High Availability (HA) state. HA Databases are necessary for obtaining that coveted place among 100% uptime websites like Google, Apple, Amazon, and the countless other always online web services. This is only possible due to database replication.

Benefit #4: Partial Backup

It is true that a secondary copy of your database running in a replication cluster can function as a makeshift backup in many situations. Hardware trouble being the big one. It can be promoted to a new role when one of its fellow cluster members suffers a physical abnormality. However, while it can and does function as a hot-spare backup in these scenarios, it is important to remember that it is not as reliable as a typical point-in-time backup. Any changes made to a master nodes gets replicated, period. Cluster members will not protect against problems that were successfully replicated to the cluster. From a hardware perspective, this is fine, as something like a bad motherboard cannot be replicated by a master node, more typical problems like table or row changes are always up to date and cannot be easily reverted using a cluster member alone. In this sense it is folly to rely on your database replication cluster as a replacement for standard backup practices.

Remember – Database Replication on its own is not a reliable backup solution. In the same fashion that RAID arrays are not file system backups. They are both designed to provide uptime reliance, but cannot facilitate all the necessary parts of a good point in time snapshot.

When Do I Need Managed Database Replication?

Managed Database Replication is a respite for business owners of all sizes who require a lean payroll alternative to developing and maintaining an expensive inhouse Database Replication solution themselves. You know your replication needs are being met every minute of every day by our support heroes who ensure the integrity and availability of your data so you don’t have hire specialists to built and support your own Database Replication cluster.

Query Stacking – When database servers reach their physical limits, beyond standard optimization practices, queries begin to stack up and wait in a queue for their turn to be processed. This slows everything down to a crawl. The website/application will start taking several seconds or in some cases minutes before the page can be successfully loaded by visitors. This spells disaster for your site as studies have proven that websites taking longer than a few seconds to load are often abandoned by their visitors instead of waiting around. This will tarnish your brand for those who have encountered such latency. Query Stacking is an obvious signal that your setup has reached its current limitations and should consider a database replication based solution.

Conclusions

Database Replication is a fundamental component of all high performance infrastructure. Websites the world over would routinely suffer bouts of downtime and extremely long wait times in a world without Database Replication. It’s a necessity and an eventuality as your website grows. Managing your replication solution is an everyday task with its own inherent expenditures. Managed Database Replication lets you focus on your business instead of maintaining the staff and infrastructure needed for monitoring and servicing your clusters needs. Peace of mind is a valuable commodity for weary website owners that Managed Database Replication aims to provide an affordable enterprise-tier solution for your website growth strategies.