You have to understand what each option gets you, and their limitations.
1. Recycle Bin and version control.
In the case that someone wants to get back an older version of a document to compare it, version control is essential. It is turned on by default (major versions) in SharePoint Online libraries. They are retained according to the settings in the library. If you are updating the document yourself all the time, it may just overwrite the same version number, so can be a little hit and miss, unless you explicitly check it out and check it in at important points, or someone else edits it (which creates a new version.)
We find this useful.
If you delete a document it goes into the site recycle Bin for (I think) 90 days, and then into the Second Stage Recycle Bin or site Collection Recycle Bin for another 90 days. So its gone after 180 days. That is enough time for most people to realise they can't find a file, and make a request. A lot of my restores have been like this.
3. Manual backup
If you have the storage and you want to capture a point in time, then this can be useful, such as after a major release. You would probably want to script it with powershell, or you run the risk of forgetting. You will typically forget or be too busy to do it right before something catastrophic happens. Not recommended except occasionally.
Depending on how many users you have and how large your tenant is, this may be unworkable.
4. Microsoft can restore your data
They backup your data as well. However, they will only restore a complete Site Collection, and they only retain it for (I think) 90 days. So this would only be useful in complete disaster times, or some disgruntled employee goes on a rampage and deletes everything. Restoring a Site colllection will overwrite all the document updates made since then
2. Third party Software
None of the above do proper retention, so if you need to ensure that your documents are retained for regulatory or other reasons, you probably need third party software.
We use AvePoints DocAve Online, and we find it mostly useful (I do not have any association with them). Choices you need to make are
- whether the backed up data is encrypted and can only be read by the backup tool (In which case you are tied to the tool)
- is the storage on their storage, or can you backup to your own location.
- Can you backup to local company storage or to cloud storage
- performance considerations.
Performance consideration aree worth talking about. On Premises you can backup the Content Databases, and there are tools for mounting a Content Database and restoring from that. Not so in Office365. Microsoft provide an API for accessing the Content, and you cannot get at the Content Databases. You have to backup each file in the site collection individually. This means that backup is Slooow, as typically a Site Collection has a lot of very small files. You will never get the sort of backup performance as on premises. In addition, Microsoft throttle users that try to access large numbers of files, including backup accounts. We recently had our OneDrive backup of 1.5TB take 50 hours to backup. you can set up multiple accounts to mitigate this to some extent, eg. for backing up different sections of your tenant, but its not ideal. I don't know any backup tool that doesn't use the Microsoft API to backup SharePoint Online/OneDrive.
With DocAve Online, we can go back into the backup schedule and selectively restore a particular file from the backup of last week, or tell people what was in a folder at a point in time. I have used this a reasonable amount as well, sometimes when people are tying to track down where their changes may have gone to.
