Redundancy Plans to Ensure High Availability of VPS

March 2, 2020

Every website depends on data to provide smooth services and keep the systems running. That’s why it has to be easily and quickly available at any given time. Effective systems ensure this accessibility at virtually any circumstance, but if they’re not designed to back up important information, it can result in disastrous consequences. While backups saved in an appropriate storage VPS can greatly help when worst comes worst, proper redundancy plans can help ensure high availability in case the primary method of accessing data becomes unavailable. The implementation of these depends on how you use the information and what failures you want to guard it against.

RAID

It stands for Redundant Array of Independent Disks and is arguably the most common type of replication. In most configurations, disks mirror each other in different ways. Usually, hosting providers choose to implement the RAID 1 array as it ensures high availability. In this model, arrays mirror one disk on another one. If one fails, the other is still available to write and serve data. The system can read from either data locations so this type speeds up reads.

With RAID, if you delete one file in one array, it’s permanent as every change is instantly applied to both disks. It’s strongly recommended for users to keep their data secure by regularly backing it up on another server via proper storage VPS. This replication method is chosen by providers to guarantee uninterrupted service, not as a replacement for backups.

Block-level

DRBD, or Distributed Replicated Block Device, mirrors entire block structures. It is a bit similar to the mirrored RAID array, but there is an essential difference when it comes to where the replication takes place. In RAID, redundancy happens below the application level and the software manages the physical storage devices and presents the application with a single device.

The configuration of DRBD is different. It is set up in a way that each hardware stack and application interface is mirrored. Component failure can be easily resolved as there is a separate machine that has data copies it can work with. If one server is cut off, the other will continue its work. But again, hosting providers choose this form of replication to ensure high availability, they do not act as proper file backups. To protect their information, users should back it up themselves on a storage VPS in case of complete system failure.

SQL replication

Users that store their files in programs that use SQL databases have access to built-in replication features. If the main server shuts down, these provide a failover system. There are two types of SQL replication:

  • Master-Slave. This is the most basic kind. There is the main database server called “Master”, which is responsible for writes and updates. Information from this server is continuously copied to a “Slave” one, which can only be used to read files. This setup can improve application performance as it allows you to distribute reads across multiple machines. With this method, backups and redundancy can work together. One can temporarily disable replication to keep a consistent state of information on the Slave and back up the data to appropriate storage VPS.
  • Master-Master. This type allows both servers to have “Master” abilities, so each is responsible for writes, updates, and changes. The load balancing system equally distributes writes, thus increasing the performance. If one server goes down, the other can still accept requests. It also can be combined with an appropriate backup mechanism.

These additional redundancy features are useful when it comes to ensuring the availability of the systems. As a bonus, they also help improve the performance of the write tasks.

Replication plans are practical as they keep the applications running when something happens to the servers. With some methods, they also boost essential tasks, so implementing them is advisable. But they are a supplementary feature that only adds to the availability of the systems. Regular backups to a safe storage VPS are still necessary to ensure maximum accessibility of the servers and websites.