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September 22, 2009


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Mike Dutch

Regarding: "(By way of an aside: does this mean a "backup" to flash drives is not a backup?)"

It's orthogonal. The definition doesn't restrict the media type (tape, disk, flash, ...). It justs notes the media is USUALLY removeable. Also note that definitions may change as industry consensus evolves. At some point, the use of B2D may exceed B2T and the parenthetical comment may need revision/deletion.

Preston de Guise

Scott - this is something that I spend most of my book either implicitly or explicitly discussing. In the intro I'm fairly blunt about it - too many companies think that by installing some backup software and hardware that they've installed a backup system . That's rarely the case, since the actual IT software/hardware is almost the least important part of a fully functional backup system. It's the human aspect (both within IT and without), the understanding of the business mappings to IT, the agreement on SLAs, etc., that all have to meld together (with that equipment/software) in order to produce a backup system.

W. Curtis Preston

Your suggest that you are going to discuss what about a copy makes it not a backup, but then you didn't actually make any points in that regard.

CDP is a copy with a log. Snapshots that are replicated are copies. I would consider both of these components of a backup system and are just as valid of a backup as a backup tape -- if not more so.

I do think that the backup system should be protected from hackers, but that's true of an old style and a new style backup system. People incorrectly assume that if it's a "copy" that someone will be able to delete it easier than something that was on a tape. Someone with intimate knowledge of the backup system could destroy either, which is why you have to protect against that person.

One final note. What NBU stores on EMC/Data Domain (via NFS/CIFS/OST) is essentially a tar ball. So I'd say that a tar ball is also an essential component of a backup system.

Preston is right. It's the system that makes it a backup, not the technology that got it there.

Scott Waterhouse

Curtis... "It's the system that makes it a backup..." Isn't that pretty much what I said? :)

A copy is a necessary but not sufficient component of a backup system.

Preston de Guise

I think the confusion lays in "backup" in the broadest, general term, and "backup" in the specific "instantiation of protection from a backup system".

I would suggest that narrowing the focus to just a single CDP instance would not satisfy the requirements of a "backup system", but yes, does satisfy a broad definition of the term "backup".

What the real crux of the matter is (IMHO) is educating companies and people to understand that a collection of random "backups" does not create a backup system.

I'd also suggest that the haziness around "backup" vs "backup system" does bring merit to my thoughts on pulling data protection activities out of ILM, and defining ILP - Information Lifecycle Protection. (https://bit.ly/bo1E4). Then it will at least be possible to agree that both CDP and backup form part of a total information lifecycle protection strategy.

W. Curtis Preston

Honestly, Scott, I wasn't sure what you were saying in this post. So I assumed that you were continuing your previous stance that was essentially (from memory) that a snapshot-only system (no matter how well managed and systemized) is not a valid backup, even if it's replicated.

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