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Merge with subsequent layer still leaves incomplete layer  XML
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Prion



Joined: 20-Nov-09 00:41
Messages: 18
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Hi James
I am having the following problem. During the acquisition of a new layer QRecall ran out of space and hence the process was terminated with an error message.
The archive was damaged and couldn't be opened until I repaired it which worked fine (phew).
I noticed there was an incomplete layer which I merge with the one that followed. The result was that I now have a more inclusive, larger layer which still is incomplete. I repeated with the next layer, same result. I am not totally sure that it has not been there before the error occurred, it possibly has been without me taking notice.

Any ideas what to try next? Ultimately, I am not too worried because the layer is quite old, but I would like to make sure that I have at least one copy of each item inside the incomplete layer that resides in apparently intact layers. (Verify is currently running).

Prion
Prion



Joined: 20-Nov-09 00:41
Messages: 18
Offline

As an addendum: Verify worked fine, but later I merged again the now incomplete, more inclusive layer and its subsequent layer - same result. Then merged three layers, the one before, the incomplete and the one after - still incomplete but no error message.

James Bucanek



Joined: 14-Feb-07 10:05
Messages: 1546
Online

Prion wrote:I noticed there was an incomplete layer which I merge with the one that followed. The result was that I now have a more inclusive, larger layer which still is incomplete. I repeated with the next layer, same result. I am not totally sure that it has not been there before the error occurred, it possibly has been without me taking notice.

Diagnosis of this situation is complicated because the layer is an old one. Recent changes in QRecall change why layers are marked as incomplete, and how subsequent captures treat them. I'll explain what's going on, and a couple of scenarios in which this can occur.

A layer can be incomplete for a number of reasons. Typically, it's just because the capture was interrupted and didn't finish. When this happens, the layer is marked as "incomplete." Items lost because of data corruption can also cause a layer to be marked as "incomplete" during the repair process. But the repair is more likely to mark the layer as "damaged," which means the good portions of that layer was reconstructed by the repair, but some items were likely lost.

Since the layer is marked as "incomplete" and not "damaged," let's assume that's exactly what it is. When a layer is incomplete, it just means that QRecall didn't finish the capture, so there are likely items that didn't get captured. The next capture will start over and will recapture any changed items, which will include any of those missed by the incomplete layer.

The first wrinkle is that this is the situation today. Older versions of QRecall were not as good about forcing missed items to be recaptured. They would be recaptured eventually, but it might be weeks before QRecall got back around to them. The newer versions of QRecall are very aggressive and force every item to be scanned (and recaptured, if needed) whenever it's capturing on top of an incomplete layer.

So, today, if you capture an incomplete layer, followed by capturing a complete layer, and then merge those two layers the merged layer will be complete. That's because anything missing from the incomplete layer will have been captured in the subsequent layer. However, if these layers are old that might not be the case.

The second wrinkle is that there may be a bug in QRecall that incorrectly marks a merged layer as incomplete or damaged. Earlier versions of QRecall were too lax about merging incomplete and damaged layers. The resulting merged layer could still be incomplete (or even damaged), yet the layer was marked as whole. Newer versions of QRecall are much more conservative about making sure that merged layer that have inherited any inconsistencies are marked as such. However, I suspect that it's a little too conservative. I've now had two user report where a damaged layer was merged with complete layer which should result in a merged layer without any missing data, yet the merged layer was still marked as "damaged." I'm currently investigating this. The problem doesn't cause any actual data loss, and I prefer QRecall to err on the side of caution, but it still appears to be a bug.

Any ideas what to try next? Ultimately, I am not too worried because the layer is quite old, but I would like to make sure that I have at least one copy of each item inside the incomplete layer that resides in apparently intact layers.

My suggestion is to ignore it. If you have any captures that follow that layer, particularly using a newer version of QRecall, then any items that weren't captured in that layer have most certainly been recaptured in some subsequent layer. You could continue to merge layers until you have a complete layer, but that strikes me as excessive.

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