* Question re DropBox

[davidm_uk]

Slightly OT but I know that there are some DropBox users on here.

As I understand it DropBox is primarily a file synchronisation application. Does this mean that if I'm using it for off site storage of backup files, and that if a file on my PC gets accidentally deleted, or corrupted, then the "copy" of the file on the DropBox folder will also get deleted or overwritten with the corrupted one? Or if I am allowing someone else to share the files can they overwrite or delete the copy on DropBox? How does the synchronisation actually work in terms of the relationship between "master and slave"?

[ColeValleyGirl]

Yes, anything that is done to a dropbox file on your PC (or any other PC synchronised with the same dropbox account, or that has access to share some of your dropbox file) is reflected in the Dropbox cloud storage.

Dropbox saves deleted files for 30 days (or longer if you pay for the 'Packrat' option) so you can retrieve a delete or corrupted file.

[tatewise]

As you say Dropbox, just like SkyDrive/OneDrive, is primarily a file synch service, and everything below applies generally.

It is irrelevant what happens to files in most locations on your PC, or any other device sharing the Dropbox account.
Only files in the Dropbox folder itself are synchronised, and only while connected to the Dropbox account.
There is no concept of master or slave but simply latest modified.
The version of the file with the latest modification date will get copied to all connected Dropbox folders.

So, yes, if a file gets corrupted or deleted and that was the latest change, then that gets propagated to the Dropbox account and all connected Dropbox folders.

However, deleted files, just as on a PC, are retained in a Dropbox account Recycle Bin and can be retrieved for up to 30 days.

As far as sharing is concerned, it depends what form of sharing you mean.
Any device logged in to the same Dropbox account has full create/read/write/delete access.
But you can allocate share access to other users/devices on a per folder/file basis, and can select whether that is full access or perhaps read only.
Users/devices with restricted access cannot disrupt the files for which they have no access.
It is similar to a PC, where each User account has different access rights to each others files, and only Public files are accessible to every User.

Thus services such as Dropbox should not be considered as a medium to long term backup resource.

[davidm_uk]

Thanks Helen and Mike for your replies.

[ColeValleyGirl]

I do disagree slightly with Mike about Dropbox's role on a comprehensive backup strategy.

It's one way to ensure you have off-site copies of your key data and make it resilient to fire, flood, burglary... anything that might affect your own local copy. It would be a very slow way to recover large amounts of data following a disaster, or if e.g. you were rebuilding your PC after a hard-disk crash, but for those with no viable alternative for off-siting their data (or who aren't organised/disciplined enough to make sure they do so manually very regularly) it's a great deal better than nothing. (All network-backup arrangements suffer from the slow speed to recover any significant amounts of data, and I haven't located a network backup service in the UK that will send you your data through the post in the event of a disaster - they exist in the States but not here, apparently).

It needs to be used alongside a regular system backup (mine is backed up completely every night to local network storage), and you must have a TESTED plan to recover from (1) a hard disk failure (or other event that requires an existing PC to be rebuilt) (2) the need to completely replace your PC in you 'normal' environment and (3) the need to replace your PC in a new environment where nothing is available to you except the data you've off-sited and software downloaded from the Internet or re-purchased. (Fire/flood etc. scenario). Plus of course (4) the recovery of a prior version of a single file or folder.

I can rebuild my existing PC in a few hours, with all the data restored from local backup (and changes since the last nightly backup recorded from Dropbox). I can rebuild a replacement from scratch in two days, including all data as long as the local copies are available to me. If I had to rely on restoring data from Dropbox, I could still be up and running in two days (PC purchase and network connectivity permitting) but would need to pull the specific files out of the cloud as and when I used them if they were needed in advance of the Dropbox sync (which takes about a month to complete from scratch).

Nirvana would be a relatively local automatically off-sited storage solution -- far enough that fire and flood and earthquake wouldn't affect it at the same time as my house, and close enough that I could retrieve my data on a external disk within a few days...

[tatewise]

I agree with everything Helen says about backup & recovery of current data in an emergency.

What I meant was that you cannot use Dropbox as a long term archive for data no longer on your PC.
Say you want to backup financial accounts or other data for past years, but don't want it kept on your PC.
You cannot save it to Dropbox, and delete the originals on your PC, as you can with Backup services, or with external removable disk media such as CD, DVD, Pendrive, etc.