Is a Copy a Backup?

Are we breaking backup in a new way by fixing it?  That's the thought I had while interviewing Bryce Hein from Quantum. It made me think about a blog post I wrote four years ago asking whether or not snapshots and replication could be considered a backup.  The interview is an interesting one and the blog post has a lot of good points, along with quite a bit of banter in the comments section.
What I mean when I say, "is a copy a backup" is this: traditionally, a "backup" changed form during the backup process.  It was put into tar/cpio/dump format, or the format of some commercial backup tool.  In this process, it made it slightly harder for it to be monkeyed with by a black hat.
I'm a fan of putting operational backup and recovery on disk.  I'm even a bigger fan of backing up in such a way that a "recovery" can simply be done by using the backup as the primary while the real primary is being repaired.  It offers the least amount of downtime in some sort of disaster.

But this does beg the question of whether or not leaving the backup in the same format as the original leaves it vulnerable in some way that putting it into a backup format doesn't.  I think the answer is a big fat no.  Specifically, I'd say that a copy is no more of less susceptible than a file on disk that's in some kind of "backup" format.  Either one could be deleted by a malicious admin, unless you were storing it on some kind of WORM filesystem.  The same is true of backups stored on tape.  If someone has control of your backup system, it doesn't take a rocket scientist to quickly relabel all your tapes, rendering them completely useless to your backup system.

As mentioned in my previous post on snapshots and replication, what makes something a backup (versus just a copy) is not its format.  The question is whether or not it has management, reporting, and cataloging built around it so that it is useful when it needs to be.

In that sense, a CDP or near-CDP style backup is actually more of a backup than a tar tape, assuming the tar tape is just the result of a quick tar command.  The tar tape has not management, reporting, or cataloging, other than what you get on the tape itself.  

I just want to close out by saying that backup products that are making instant recovery a reality are my favorite kind of products.  These include CDP and near-CDP style products like SimpanaZerto, Veeam, AppAssure, RecoverPoint, and any of the storage array or storage virtualization products that accomplish backup via snapshots and replication. This is the way backup should be done.  Backup continuously or semi-continuously, and recover instantly by being able to use the backup as the primary when bad stuff happens.

One thing's for sure: you can't do that with tape. 😉


----- Signature and Disclaimer -----

Written by W. Curtis Preston (@wcpreston). For those of you unfamiliar with my work, I've specialized in backup & recovery since 1993. I've written the O'Reilly books on backup and have worked with a number of native and commercial tools. I am now Chief Technical Evangelist at Druva, the leading provider of cloud-based data protection and data management tools for endpoints, infrastructure, and cloud applications. These posts reflect my own opinion and are not necessarily the opinion of my employer.