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Software components for data protection, secure storage and transfer

multiple uploads of same file in Wuala over CBFS

Also by EldoS: CallbackFilter
A component to monitor and control disk activity, track file and directory operations (create, read, write, rename etc.), alter file data, encrypt files, create virtual files.
Posted: 08/07/2012 11:15:35
by Jim Henderson (Basic support level)
Joined: 08/07/2012
Posts: 2

I am using Wuala to host the installers for free programs for linguistics and translation. (Wuala account is LangTran).

Wuala now uses CBFS to provide filesystem integration, and I set my remote Wuala cloud storage to appear as R: on my Windows XP SP3 box.

(Wuala version is Release "Wollishofen", PC 407 (OK) and CBFS supplied by Wuala is

I use Ketarin to check the installers that I monitor, and when any are updated, Ketarin downloads them and writes them to the appropriate folders within Group folders on my R drive. The Wuala client uploads these to the cloud for me.

For small files this works superbly, but for files over about 100 megabytes, the Wuala client starts uploading the same file many times, with different percentages of progress showing. I have written to Wuala about this, but have not received any resolution yet.

I thought there might be a timeout inside CBFS that makes it start again on a large file, but the Wuala software doesn't notice this properly.

I read a thread on this Eldos site about multiple threads working on the same file and the need for synchronization to be applied, so I thought some of you might have some ideas about how Wuala could check up to see what is happening. (The problem happens with large files, whether it is Ketarin or FreeCommander or Windows Explorer that writes the file to the R drive for upload by the Wuala client to Wuala.com.)

The screenshot shows the uploads monitor, Wuala client window and some others.

Thanks for thinking about this issue,
Posted: 08/07/2012 11:24:41
by Eugene Mayevski (EldoS Corp.)

CBFS doesn't write "files" - it writes blocks of data passed by the application. It is possible, indeed, that some application passes a large block (say 16 Mb in single block) to CBFS, which forwards this block to Wuala. Then Wuala writes this block synchronously (instead of caching it locally and uploading to the server) and the callback operation expires. In case of timeout CBFS must report an error to the OS, so it's not clear why an attempt to rewrite the file happens. Surely this is not CBFS' initiative to write the file again.

So I can confirm your assumption about timeout with 95% probability, but resolution is definitely up to Wuala developers - CBFS acts merely as a router of requests here.

Sincerely yours
Eugene Mayevski
Posted: 08/08/2012 03:33:21
by Jim Henderson (Basic support level)
Joined: 08/07/2012
Posts: 2

Thanks, Eugene, for those explanatory comments. I'll continue to press on with Wuala staff.




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