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Backup: protecting your investment in learning

Safety of your knowledge stored in SuperMemo

Knowledge you store in SuperMemo might belong to your most precious data on your hard disk! After all it cost you months or years of editing and repetitions. You must continue your repetitions indefinitely to make sure you do not forget what you have learned. This is why backup skills are so important!!! 

The fastest way to backup your collection is to use Shift+F12 (File : Tools : Quick backup). You should make a copy on a different hard disk every few days and on other media every month or so. You will quickly notice that floppy diskettes are not enough to store all your knowledge. It is then highly recommended you use some other high-capacity storage device (e.g. CDR recorder)

To quickly copy your collection to another location, you can use File : Copy collection (Ctrl+Shift+C)

Multimedia backup

If you add a great deal of multimedia files to your collection, you can also use File : Tools : Semi-copy to save your non-multimedia files. Such a copy will take less space and preserve the structure of your collection without storing images, sounds, videos, etc. Semi-copy cannot be used as a replacement for Copy collection. From time to time, you should back up the entire collection to be sure your multimedia files are not lost.

Learning process backup

If you are using a commercial collection available on CD-ROM, you can save lots of space if you backup only the learning process. You can do it with File : Tools : Export : Learning process. Note that this will not preserve changes you have made to texts in your collection. In case of a mishap, you can reinstall your commercial collection and restore the learning process with File : Tools : Import : Learning process. For example, the full semi-copy of Advanced English takes nearly 50 MB while the learning process backup takes from 0.1 to 3 MB depending on how much work you have put in repetitions.

Using WinZip, PKZip, etc.

If you would like to use archiving tools to reduce the size of your backup, remember to do the following:

Example: Archiving with Windows Commander

To archive your Physics collection with Windows Commander by Christian Ghisler do the following:

Frequently Asked Questions

(Adam, Australia, Tue, May 22, 2001 6:49)
I want to optimize my backup strategy. When I do repetitions only, and do not modify anything, I could probably use export/import learning process only. How could I export/import a subset of the collection, like newly added knowledge elements, including sound/html files (assuming I only use the same set of templates)?
It is always safest to make a full copy of the collection. If you do not do any editing, File : Export : Learning process will suffice to back up the learning process. Export learning process cannot be executed on a subset of elements. If you want to backup only a newly created branch, you could just transfer this branch to a new collection but you must be cautions as some global settings are not subject to transfer. In addition, restoring such a backup is not trivial. You will need to transfer the branch back to an earlier backup of the entire collection

If SuperMemo loses its vital files, you may need to restore the whole collection from a backup
(Juarez Barreto, Brazil, Friday, August 30, 2002 3:35 AM)
SuperMemo displayed the following error: 
  "Collection files missing! 
  Try to restore files that you have moved or deleted"
On opening a collection, SuperMemo checks if its vital files are in place. If any of these is missing, the above error will show. Vital files are those that make recovering the collection impossible. For example, the text.reg file contains the text of your elements. If this file is missing, SuperMemo will not be able to recreate the texts used in your collection. This will render it useless. Most likely reasons for the above error: 

  1. you moved the kno file without moving the associated folder. For example, if your collection is Meus then it is made of the file Meus.kno and folder [Meus]. If you move Meus.kno to the root of your c: drive and then try to open Meus.kno, SuperMemo will protest the absence of the [Meus] folder by displaying the message above
  2. you deleted, moved or renamed the folder associated with your collection (e.g. c:\meus associated with c:\meus.kno
  3. due to a virus, software or hardware malfunction, one the the vital files was deleted or its size was set to zero If you are unable to restore the deleted folder or files, you will need to resort to your most recent backup of the collection

Important: If you are not fluent with files and folders, it is safer to copy or move SuperMemo collections with tools available on the File menu (for example, File : Copy collection). Otherwise, it is very easy to pick the kno file in Windows Explorer and separate it from the rest of the collection. The error message as above will result

(Przemek S, Poland, June 8, 2000)

I used to regularly back up my Advanced English on a second hard disk. Today I tried to restore my backup and ... it looks as it is empty! Only one element inside! Help!!!


There is a frequent mistake users make. To backup a collection, you need to copy both the kno file and the associated folder (e.g. file ae.kno and the folder [ae])(see: Collection files). Some inexperienced users copy only the kno file which is just 20KB of data! If you try to open an orphaned kno file, SuperMemo will reconstruct an empty folder structure.

To avoid this problem: Always back up collections with File : Copy collection or File : Tools : Quick backup. Do not use external tools unless you understand Windows, files, folders and SuperMemo very well!

To resolve the problem: it is possible the original folder associated with the kno file still exists on the hard disk! You can search for some files characteristic for SuperMemo (e.g. burden.dat or sm8opt.dat). Make an inventory of all kno files (search for *.kno) and all SuperMemo collection folders (search for burden.dat) on your hard disk. Once the inventory is made, try to carefully match up knos and folders and copy kno files to match the folders. Chances are that File : Open on one of these files will restore the lost backup. Note that you can easily find empty collections by checking the size of burden.dat. This file contains repetitions and is zero-sized on collections with no learning process

You can easily copy SuperMemo to a diskette (#5520)
(Jack B., Sun, Jun 24, 2001 2:20)
After getting the program downloaded, may I simply pay for a backup diskette sent to me?
You can create your own backup diskette in a minute by simply copying the downloaded file onto a blank disk. For example, SuperMemo 2000 download file (sm2000zip.exe) is only 1.3MB in size and should fit on a diskette

Disappearing material (#6428)
(hojinil, South Korea, Wednesday, April 11, 2001 4:29 AM)
I used Add New and I added lots of stuff but next time when I opened collections I couldn't find any of them. It was gone!
Please make sure the following two conditions are met: 

  1. You are not copying or moving files behind the back of SuperMemo (e.g. with Windows Explorer) 
  2. With File : Open collection, you go to the exactly same location where you last left your collection 

If some files are moved or deleted behind the back of SuperMemo, it will often attempt to recreate missing files and open the collection regardless. Unless you delete your collection or delete its folders, your learning material should remain safe