Since EMC formed the Data Protection and Availability Division by combining the Data Mobility Business Unit and Backup Recovery Systems, I’ve been having a conversation over and over again.
You could say I’ve been having it continually.
So, let’s spend some time, write it down and get pedantic.
Continual means ‘repeatedly but not constantly’ while continuous is ‘ a sequence without interruption.’
The difference shoots past most people without mattering, but to us it does matter and if you can keep the difference in mind, congratulations, you’re now infinitely smarter than anyone who has ever used the term ‘Near CDP.’ Which doesn’t make any sense even if you substitute the letter C representing continuous for a letter C representing continual, so long as the letter C involved immediately follows the word ‘Near’.
That being said the conversation I’ve been having is if you make something continuously available, RTO = 0, does that make it continuously protected?
The answer is of course, no.
As we look at the cloudy application vendors re-writing their apps to span datacentres which may or may not be available on Christmas eve, thereby preventing thousands of ‘Buffy The Vampire Slayer’ binge viewing sessions, we notice that for a number of years with existing application clustering software and the distributed cache coherence technology of VPLEX, enterprises can do the same thing.
Active/Active configurations spanning datacentres with the VMware HA/FT, Oracle RAC, MS Cluster or what not, with what you have today providing continuous availability.
But just because you have continuous availability doesn’t mean you do not need data protection. Same as it ever was versioned replicas of that data are required to ensure you can meet the variety of recovery points which come with user or system errors.
That data protection might be continuous, like with RecoverPoint CDP or it might be continual, like with a backup applications such as NetWorker & Avamar or snapshots or NDMP backups and so on.
Continuous availability requires data protection regardless of if it’s in your datacentre, your own cloud or someone else's cloud. The choice of continuous or continual data protection, or a combination there of, is entirely up to you.
And now that’s written down I’m going to start asking people if they want uninterrupted data protection or repeated data protection?
Not a C in sight.