Feeds

Can replication replace backup?

Well, since you ask...

  • alert
  • submit to reddit

Next gen security for virtualised datacentres

You the Expert We are asking Reg reader experts - and a chief technology officer - to have a look at interesting issues in storage. The first topic is:

Can replication replace backup?

Backup started as saving a copy of data to tape. For many users it now means saving a copy to disk, either as a straight file backup or as a virtual tape backup. In both instances data is being moved from one disk to another. That’s what replication does too, but without the complexities of backup software and restoration using backup software.

Does this mean you can dump your backup software and rely completely on the much simpler replication idea?

We asked four storage experts what they think about this - and you can read their musings below. But we are very interested in your thoughts too. We are keen to expand our line-up of Reg experts. Show us what you are made of!

Chris Evans

Chris Evans

Independent storage consultant

Initially, the obvious answer to this question is no; replication can’t replace backup; that’s not what the technology was designed for. Replication was developed to migrate data between storage arrays in the event of a physical failure in a storage device or with the site in which the storage device is located. The process of replication creates an exact replica of data at the source location. This is achieved either synchronously or asynchronously; effectively as soon as a change is made on the primary array is it permanently made on the secondary.

Traditional replication goes against the premise for which backups are taken - to recover to a point in time at which data was lost or corrupted. The second point (corruption) is probably the most important reason why traditional replication can’t replace backup - corrupted data would be replicated to the remote site before there had been any chance to identify it or to stop the replication that had occurred.

However, of course, replication is no longer simply transmission of changed blocks of data from storage device to another. Continuous Data Protection (CDP) logs changes in primary data and stores those changes for a finite period of time, enabling recovery to be made at a secondary site to any time in the past - assuming enough data has been retained. This is fundamentally different from traditional replication where the changes are usually simply overwritten immediately.

In summary, traditional replication will not replace backup - however, CDP-style replication may just have a chance.

Chris M Evans is a founding director of Langton Blue Ltd.. He has over 22 years' experience in IT, mostly as an independent consultant to large organisations. Chris' blogged musings on storage and virtualisation can be found at www.thestoragearchitect.com.

Gartner critical capabilities for enterprise endpoint backup

Next page: Evan Unrue

More from The Register

next story
The Return of BSOD: Does ANYONE trust Microsoft patches?
Sysadmins, you're either fighting fires or seen as incompetents now
Microsoft: Azure isn't ready for biz-critical apps … yet
Microsoft will move its own IT to the cloud to avoid $200m server bill
Shoot-em-up: Sony Online Entertainment hit by 'large scale DDoS attack'
Games disrupted as firm struggles to control network
Cutting cancer rates: Data, models and a happy ending?
How surgery might be making cancer prognoses worse
Silicon Valley jolted by magnitude 6.1 quake – its biggest in 25 years
Did the earth move for you at VMworld – oh, OK. It just did. A lot
Forrester says it's time to give up on physical storage arrays
The physical/virtual storage tipping point may just have arrived
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
5 things you didn’t know about cloud backup
IT departments are embracing cloud backup, but there’s a lot you need to know before choosing a service provider. Learn all the critical things you need to know.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?