Continuous Data Replication for Safeguarding Data in the Cloud

How do you do your data back-ups at the moment – is it just when you remember, or maybe every day at 5pm sharp? Defining a set time at which to transfer your data to secure storage has the merit of making sure you at least have some data back-up. However, it’s clear that if there’s a problem, the data you can recover will only be as fresh as your most recent back-up. In this example, that could mean the loss of up to 24 hours’ worth of data. In some cases, that’s just too long. So organizations have been decreasing the back-up ‘windows’ to avoid such a risk. With solutions available on the market, those windows have been getting smaller and smaller, until guess what – the window disappeared completely. The age of continuous data protection is now upon us.

Continuous or Nearly Continuous?

Some solutions really are continuous – they record changes in your data immediately. Others however are more properly referred to as ‘near-continuous’ (even though the vendors concerned still call them continuous). What’s the difference? With continuous data replication (CDP), when data is written to a local disk, it is written to a second storage resource, like the cloud, at the same time. By comparison, near-continuous data replication takes ‘snapshots’ of a system at regular intervals, and transfers those snapshots to safekeeping. In other words, near-CDP still has those backup windows, even if they are relatively small (maybe a few seconds.)

How Does This Work for Cloud Back-Ups?

The big attractions of cloud data storage for back-ups are its reliability and expandability. It’s also a big relief when you no longer have to worry about setting up and managing your own servers in your own remote location. However, if you’re constantly sending data or data snapshots up to the cloud, what about network bandwidth? CDP solutions have an answer for that. Instead of trying to store a complete image of all your data for each change or snapshot, more advanced CDP only transfers what changed. So if you changed 2 bytes of a 20 Gigabyte file (think about large databases and CAD files), then 2 bytes are all that must be uploaded.

Restore Granularity

If you can continuously back up your data to the cloud with the right CDP solution, what about getting it back? Traditional data back-ups often suffer from inflexibility when it comes to recovering specific files or bits of content. Tape storage is a case in point. Although it’s cheap and can accommodate huge volumes of data, you may have to restore an entire data back-up just to be able to then pick out the information that really interests you. CDP solutions offer a more agile solution. They allow users to directly recover different objects of particular interest. That might be the whole disk snapshot, or it might be a particular database, a mailbox or even a single email message.

More Protection than RAID? Test Anyway!

Compared to RAID systems, CDP has a more intelligent approach. A RAID system with its multiple hard drives copies data diligently. However, if data become corrupted, the RAID system then diligently copies the bad data. CDP on the other hand stores good versions of your files and content. If you make a mistake or if a virus infects your system, CDP lets you access healthy versions of your data that were stored before. CDP also makes it easier to test that you can indeed recover usable data, should you suffer a local crash or attack. But as for any data back-up solution, do real, meaningful tests with CDP to make sure it works properly for you too.