Power failure: Nothing more to learn, but there are still outstanding elements

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Question

I was doing my daily repetitions, and suddenly my neighborhood experienced a power outage while I was almost already done. (more details below).

Answer

In case of the power failure:

  1. create a backup of your collection (e.g. Ctrl+Shift+F12)
  2. do File : Repair collection
  3. for peace of mind, press F11 for a while to inspect your elements from various portions of the collection
  4. for peace of mind, make another backup (post-repair)
  5. start learning
  6. if you see nothing suspicious in 3-4 hour of work, you stand 99.9% chance your collection is ok

You may need to add extra time to collection verification if the outage happened during data-processing-intense times (e.g. collection repair, collection rename, processing of large elements in the browser, etc.).

    • The outage happened right after I had just graded myself and clicked "Next repetition". So probably some data was being written on the disk.

Follow-Up

After two days, it seems that my collection is fine - no errors are shown when I attempt to repair it, and I haven't noticed any suspect behavior or mismatched elements. Luckily it was a false alarm. Anyhow, thank you for getting back to me so quickly.

  • Also, lesson learned (and advice to other people): if you are not working with a laptop, get an UPS (Uninterruptible Power Supply) as soon as possible, one which will stabilize the current (as to avoid harmful jolts/surges/spikes/noise) and supply your pc and monitor with at least 10 minutes of power. And if you already have one, check the battery regularly! I have one and thought I was covered, but it failed nonetheless because the battery was not good anymore, I had no idea.

Technical

SuperMemo keeps most of its data on the disk and keeps in memory only currently needed data. Large structures that need speed (e.g. priority queue) need to be kept in memory, but are regularly updated and can be repaired with Repair collection or easily fixed manually. Probability of serious data loss at power failure is little. There probably weren't any reports of data loss that would not be recoverable (except for a loss of a single elements, single text, etc.).

More details of the power failure

When everything went back to normal and I restarted Supermemo, I was greeted with this:

Discrepancy.png

The workload shows just one repetition left. The Outstanding field shows 129 repetitions left. When I click "Learn", it says "nothing more to learn", basically validating what the workload says but ignoring what the "Oustanding" field says.

I clicked on the workload field to see if anything was wrong. This is what I got:

Subsetelements.png

Cannot make head or tails out of it. It shows 234 elements, which was the total number of repetitions I had to execute today. The rest, I don't know what it is.

And if I tell Supermemo to show me those outstanding elements...

Outstanding.png

...Zero. No elements.

Zeroelements.png

I tried to completely repair my collection (every box checked, including rebuild lexicon and verify repetition history) and this is the report:

http://pastebin.com/nxrbsN5A

No errors whatsoever.

So I tried a little experiment. I advanced the date by one day, and opened Supermemo. Apparently, now everything is fine! The 18 September 2011 field is completely clear, the "ghost" repetitions disappeared, and everything seems back to normal. The repetitions are now 232 instead of 231 because evidently the one repetition I had left carried over to the next day.

Experiment.png


So, apparently my collection is fine. But there's evidently something off-kilter here, at least so it seems.

Now, my question is very simple: should I be worried about the integrity of my collection? Should I revert to my most recent backup? Or can I safely assume that that little hang-up was nothing more than a little glitch which will have no lasting effect on my future learning?

Any suggestions?

Thanks.

Hints

  • The above will be analyzed, in the meantime, you could work with the "damaged" collection to see if all is ok. Naturally, if the work loss due to the backup revert is just minutes, you may opt for returning to the backup.
    • I checked the collection and apparently everything is fine. Will see in a couple of days if that's still the case, but I'm optimistic.
  • Workload window and Outstanding probably display data from a different source. That discrepancy should be resolved with Repair collection. If you got no errors, perhaps all that was needed was to build a new outstanding queue (SuperMemo does it at the beginning of each day). That queue is only used to speed things up. The raw data is kept elsewhere. Sometimes just one byte of wrote data in the sequence of elements disrupts the whole chain. Then Repair collection is needed to repair the break.
    • Repair collection didn't actually do a thing, as I posted above. Or to be more specific, the very first Repair I ran found THOUSANDS of errors (unfortunately it didn't occur to me to copy/paste it), and all the subsequent ones found none.

Question from another user

I'm sorry I can't help with this, but can I ask you how you managed to memorize 245 items/day ? That is huge, and you are only four months in...

  • Hi! Actually, I'm about 4 years and half in (not counting another couple of years when I was just fooling around on and off without real daily commitment), not four months in. It appears like that because my old collection got severely damaged, with many unreadable elements, inaccessible files and a damaged emptyslots.dat file, so in order not to lose 4+ years of work I had to:
    • Get rid of the problematic elements which rendered my collection unusable (one by one - still shudder remembering that day, boy did I burn the midnight oil with that one)
    • Transfer the "good" elements to a completely new collection
    • Export the learning process from the old collection into the new collection so I wouldn't have to start from scratch (ugh!)

The repetition history of each item/topic remained intact, but the data relative to the items/day/speed/cost and of course the age of the collection itself got reset.

This is a detailed report of what happened if you're interested:

http://wiki.supermemo.org/index.php?title=Power_Failure._Hard_Disk_Failure.

Anyway during those years I learned an average of 100-150 items per day, so that's not much far afield from reality. I use mnemonic techniques, screenshots/videos from documentaries/tv series/movies, contextual learning, incremental essay writing, and another bunch of stuff which allows me to keep leeches to a minimum. We can continue this discussion in my talk page if you wish.

Hint

If you go for Advanced English (40,000 elements) and the goal of 1-3 years, you are likely to battle very high item loads. 500 it/day is not unheard of. The official stand is 100 items per day (40 min) for AE in 4 years. However, it is highly individual. Bigger numbers may indicate worse mnemonic skills, no leech management, or ... higher self-criticism (which is usually good for long-term outcomes). in other words, much/many is not always good.

Comment from an Advanced English student

I finished Advanced English (which gradually morphed into my general-purpose personal collection) in a year and a half with a very manageable workload. I am now a copywriter/fiction writer in English on the side. I think I can make a couple of observations, since the subject came up. Feel free to move this wherever you see fit if you find it off-topic (it probably is).

  1. Advanced English has many, many field-specific elements (math, geography, geometry, medicine, zoology, botany) which can be safely dismissed if you don't need them. (ie. "math: math: f(X) in" or "bot: vegetable of the cabbage family whose swollen stem is used as food (Lat: Brassica oleracea)")This can whittle down 2000/3000 elements right away and will considerably reduce your frustration. Also, some items may not be useless enough to be dismissed, but unimportant enough to be given long intervals (ie. 300 days). I usually do this with animals, like obscure species of birds or fishes.
  2. I already had a fluent command of the language and read in English every single day. Can't say that didn't help.
  1. Expanding on the above, short, one-word items are useful, in my opinion, only if they are univocal - ie. "knife (utensil)". "knife" can only mean one thing. But what about polysemic words like, say, "pepper"? It can be a spice. It can be used as a culinary-related verb, as in "peppering the pasta". It can be a synonym of "barrage/bombard". In the context of a speech, it can be mean "enrich" (ie. "He peppered his speech with jokes."). How can you battle memory interference? Answer. Sample phrases showing the word in context. A lot of them. Paste them in Supermemo, shorten them as much as necessary (but not so much as to lose context), and ALT+Z the hell out of them (incrementally, if there's more than one word)
  2. Passive recognition (ie. reading topics) is almost as useful as active recall, especially if writing is your thing. Reading and re-reading the phrases gives you a sense of rhythm and style, which words alone cannot simply give you. (You should of course stagger the topics accordingly - I try never to exceed 30 per day) What I do when I'm presented with a topic is close my eyes, try to remember as much as possible, and then verify. Then I reschedule it.
  3. Daily commitment is vital. I never, ever missed a single day. Ever.