Information lost after an unexpected shutdown of the computer

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Problem

Simon J. wrote:

I was working with SuperMemo when my computer shut down unexpectedly. After I started it up and returned to SuperMemo, to my horror, some data was missing. I have a backup from the last month, but I have done so much work since that I feel sick thinking I will need to go back to my backup.

Here are the problems I noticed:

  • when I click Learn, I get a report on the end of learning
  • when I click View : Outstanding, I get nothing!
  • in Workload Calendar, I have all repetition numbers, but I cannot see what repetitions are due for particular days
  • when I click History, I get an empty window

I know I can try File : Repair collection, but I am not sure it is a good idea at this moment. I will make a backup first, but this collection is a few gigabytes (lots of pictures and videos).

What do I need to do next? Do you think it would be safe to stay with my collection? Or is it better to somehow transfer the effects of my work back to the backup? (new articles, pictures, etc.)

Answer

All problems that you list show that the shutdown occurred at a very unlucky moment when SuperMemo tried to write down 4-6 files with data such as History.sub, outstanding queue, and Repetitions.dat (for details see: Collection files). If the process of writing those files, which takes milliseconds, is interrupted, they can all get damaged (e.g. filled with zeros).

These are the files that for performance reasons are kept all in memory while you use the program. This is why they are most vulnerable. However, there is also redundant information stored in other files and Repair collection should be able to restore all data missing.

The only file that you will not restore is History.sub that will be filled out with new data as you visit new elements. You do not really need it.

If your repairs finish and there was not other damage then what you report, your collection will be like new. Do not panic if you see a huge number of errors. If you have thousands of elements, each will report its repetitions missing in the schedule before they get restored.

Please report back if all is ok to complete the documentation.

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