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Comment by joebananas | Hacker News Reader

> but they don't really understand how it acts as a backup system too.

Maybe your parents are just more sophisticated than you and know the difference between redundancy and backups.

You're playing semantics. Fundamentally all "backups" are just storage redundancy.

The difference is isolation. If I accidentally rm a file on a RAID, which is redundant, but not a backup, it's gone for good. Backups protect you by providing a distinct interface to >= 2 copies of a piece of data, this provides greater protection against malice, mistakes, and hardware failures.

As you say, RAID (specifically RAID level 1) is redundancy.

Time Machine is a form of generational/chronological backup.

Apple has stated that Time Machine is not archival. I wonder is this new patent is referring to an extension of TM, to the cloud, to provide something as close to archival as can be achieved.

This is equivalent to a version-controlled FS with storage redundancy.

Dropbox also lets you go back and open past versions of all your files, meaning that anything in your Dropbox is effectively backed up as well.

Versioned storage isn't a backup, but it is quite helpful. Additionally Amazon S3 does redundant storage ( http://aws.amazon.com/s3/#protecting ) but in the end you're relying on a single service with a single account.

I still say Dropbox provides a legitimate backup, consider the features my free Dropbox account offers:

  (1) Redundancy - All files in your Dropbox are saved on every computer and stored on Dropbox's servers
  (2) Accessibility - Files in the Dropbox can be reached from any computer with internet access via a browser and downloaded
  (3) Versioned Storage - Every saved version of every file in the Dropbox going back thirty (30) days is available online
  (4) Deletion Protection - Every file in the Dropbox is available online and can be restored, even after the file is deleted from the computer and removed from the dropbox

I may be missing something, but what exactly does a "true" backup system do that Dropbox doesn't?

You're ignoring that DropBox has access to your original copy on your computer and can just delete that one when it goes bezerk and deletes the cloud copy too. ;)

With that said once a month I copy my DropBox directory to an external hard drive and call it good enough for my data.

True, I hadn't thought about that. Have you heard of it happening before?

With that being said my backup dataset is way too big to make Dropbox a cost-effective solution so I also have Backblaze account that backs up everything including the local copies of my Dropbox, so personally I'm ok.

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