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Bernd Raab55 post(s)
#05-Aug-22 06:51

Due to a computer crash caused by a power failure while I was working on a Manifold 8-project, the project can no longer be opened. In Manifold 8.0.32.1 the error message "unknown error" appears. In Manifold 9.0.177.4 some components are loaded, then the opening aborts with the message "cannot load data". Is it possible to restore the project or at least parts of it? There is also no temp file available.

Any help would be appreciated.

dale

594 post(s)
#05-Aug-22 10:45

Have you tried linking, rather than opening the project? I have a memory of recovering data that way years ago.

adamw


10,126 post(s)
#05-Aug-22 14:02

You can contact tech support and send them what remains of the file, they will then try to recover what they can. I wouldn't hope for much, usually only some of the small components can be recovered. Sometimes it's the small components that are the important ones, though.

Bernd Raab55 post(s)
#07-Aug-22 15:46

thank you both, but I rebuilt the map again, it's a bit annoying but successful.

danb


1,946 post(s)
#08-Aug-22 02:06

I am not sure if the types of issues with corrupted maps tend to fall into particular pathologies, but if so would Manifold ever consider releasing a tool to help users recover data in such cases?

Perhaps the types of issues encountered run technically much deeper but just an idle thought.


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Dimitri

7,066 post(s)
#08-Aug-22 06:24

The issues run much deeper. That's one reason (among many) why 9 has a different .map structure and radically different data access infrastructure, to harden interactions against things like power failures. It's far better than 8, to the degree that if I do have a power failure (or a surprise Windows update and reboot...) on a machine I've neglected to protect with a UPS, the last thing I worry about is corruption of any 9 projects that were open.

But still, it's a good idea to use a UPS even with 9. [Writing this on a machine running 9 but without a UPS... had to change the battery on the UPS but haven't gotten around to shutting down the machine so I can plug it back into the UPS. :-) ]

adamw


10,126 post(s)
#08-Aug-22 12:43

Our answer to these issues is a completely different approach to saves in 9. 9 anticipates potential power losses and takes explicit measures to protect data integrity in case they occur.

We do have tools to recover data from damaged MAP files in 8, but they are pretty complicated to use. It is unclear how to make them less complicated to use without also making them recover much less data (as in, we could perhaps create a tool that would just try to "recover everything automatically", but it would not recover much, the real process of recovering data needs human input to be successful). That's why we keep these tools internal.

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