If you ever used OneNote, you probably wondered why there is no “Save” button and why your notebook becomes so huge. The answer can be found in the principle how OneNote stores its data. The rule of thumb for OneNote is that all data must be stored safely. It means three things:
1. All notes should be always saved.
2. They should be never deleted.
3. And you should be able to restore any version of your notes.
So what happens when you enter your note in OneNote?
First of all, it goes to cache. Cache is an important part of OneNote, it keeps all immediate changes to your notes, so we don’t recommend messing with it. Don’t touch cache file unless you really need to move it to another place (e.g. another hard drive with more space). If you move the cache file, make sure its new home is on a non-removable hard drive and neither you nor other users can delete it by mistake.
When OneNote sees that your note dropped into cache, it begins saving it. All your notes can be stored in 3 places. Seems a bit redundant but when it is about your notes, it’s better to be on the safe side.
The main storage is .one file that is stored wherever you decided to keep your notebook. Each .one file represents a section within your notebook. The way your sections are sorted is defined in a special file that is called Table of Contents with extension .onetoc2.
Your .one file contains two things:
1. List of pages
2. All of your pages within that section. But not just pages – rather all revisions of them.
What is a revision? A revision is a new copy of your file with any changes compared to a previous copy. If OneNote detects that you edit a file, it saves a new revision of it. How often it happens. Pretty often, I’d say but it depend on where your OneNote notebook is stored. If you are working with a local copy (that’s on your PC), OneNote saves it every 3 seconds. If your notebook is stored on a local network, it is saved every 10 seconds. If it is a SkyDrive notebook, OneNote syncs it from every 20 seconds to 1 minute max (depending on whether you keep typing or not).
In other words, every 3 seconds OneNote creates a new current copy of a page you are working with. No wonders your notebook can become huge, especially if you have a lot of images or multimedia – they are all saved every 3 seconds again and again! Good news is that sometimes OneNote optimizes your notebooks to merge revisions and clean up some space.
OneNote makes revisions available to you as Page Versions. Page Versions are created not so often in order to provide a manageable history – it would be a little hard to search every-3-second copies! Page Versions are created every one hour or when another author edited a page. Microsoft engineers posted a very detailed explanation in MS Office Forums
Another place where your notes are saved is Recycle Bin. That’s where your deleted pages go to. OneNote’s Recycle Bin is not the same as your computer’s recycle bin, you can find it in Share – Notebook Recycle Bin. Click it to find all of your deleted pages and sections for the last 60 days. You can empty it anytime or completely turn off for selected notebooks.
Backups is the third place where OneNote stores your notes. By default, the notebooks are backed up every day. You can find settings for backup in OneNote Options – Save & Backup. We are often asked, what is “Number of backup copies to keep”? By default it’s two but it does not mean that you will have two identical copy: OneNote will keep your most recent copy and a previous one. If you choose 1 copy, it will store only the last copy. If three, then 3 most recent copies.
Most of settings for saving your notes are located in OneNote Options – Save & Backup.
Since we in Outline for iPad use the same format and data structure as OneNote, your notes in Outline are equally safe (add to this Dropbox that also keeps all versions of your files).