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Problem with doing CRC/Binary compare on UNC folder

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  • Problem with doing CRC/Binary compare on UNC folder

    I am comparing two server contents using UNC (\\servername\share) format.

    If I do a simple date/time comparison, it works fine (And reports in sync).

    If I do a CRC or binary compare, I get a whole heap of "cannot open file" errors on one server. That is despite that server and folder and file being accessible in windows.

    Even using mapped drive letters does not fix the issue.

    I am using latest stable version of BC.

    Edit: I have checked the previous version and it has the same issue.

    It appears to be limited to 1 particular server that is causing the problem, although I do not understand why, as the user I am logged in as on the Windows machine has full privledges on the server.
    Last edited by Dion; 26-Jul-2010, 07:17 AM.

  • #2
    Hello Dion,

    Checking by timestamp and size only looks at file attributes, and does not need to read or access the entire file. Running a binary comparison or other content compare would require downloading the file locally to a temporary directory. On the machine running BC3 (3.1.11?), are you able to download both files using My Computer and copy it to your desktop?
    Aaron P Scooter Software

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    • #3
      Hi Aaron.

      Yes I am running BC 3.1.11; and yes I can access both files.

      I am using BC to verify a file copy, and it is the "source" of this file copy process that is giving the error, so it has been able to "read" the files previously.

      The error is like the following:
      26/07/2010 11:11:28 PM Unable to compare 20080131 - Skunkworks stand.pdf: Cannot open file "\\media\Records\Receipts\Furniture\20080131 - Skunkworks stand.pdf". The system cannot open the file
      Yet copying and pasting the file name/path in a Run window in Windows 7 opens the file no problems.
      Last edited by Dion; 26-Jul-2010, 03:40 PM.

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      • #4
        Actually, I just tested the file comparison "individually" (i.e. found that file in the tree, right clicked and selected "Compare contents" to compare that single file, and it works fine!

        I also just compared the next level up folders \\media\Records\Receipts and that works fine as well.

        It seems to only generate the error when comparing in bulk? (i.e., comparing the whole share \\media\Records)

        Does BC use multiple threads or something, perhaps my server (its actually a Thecus N4100Pro NAS) is limiting concurrent connections? Is there a way to prevent that in BC?

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        • #5
          Hello,

          Do you have one tab open running one background comparison? If so, that should use only one thread.

          If you have multiple tabs, or start multiple content comparisons (using the right-click menu, or starting a content compare while a background compare is still running), then it would use multiple threads.
          Aaron P Scooter Software

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          • #6
            Originally posted by Aaron View Post
            Hello,

            Do you have one tab open running one background comparison? If so, that should use only one thread.

            If you have multiple tabs, or start multiple content comparisons (using the right-click menu, or starting a content compare while a background compare is still running), then it would use multiple threads.
            Only the one tab.

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            • #7
              Hello,

              Are you double clicking any files, or accessing them with another program (perhaps a virus scanner) while the background content comparison is still running? One tab, running the background content comparison, should be using only one thread.

              Are you using the latest firmware and drivers for your NAS device? Some NAS devices have non-standard behavior when it comes to access, although this is the first I've heard of one not working during a background scan, but allowing access to files when double-clicked and viewed in BC3.
              Aaron P Scooter Software

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              • #8
                No I'm not double clicking on anything nor running virus scanner (that was the first thing I disabled). Most of the time it is BC running by itself.

                NAS device has latest firmware. This is the first time I've had anything "access related" as a problem with it.

                Like I said above, I can get it to scan if I do folder by folder, but not entire shares; and I can access the files no problems (and copy them off to another location). In fact all I am doing is having copied the data from the NAS to another device, I am checking (verifying) the copy by trying to use BC.

                It seems to be only towards the end of scanning (i.e. after it has done 50% of the total share) where it has problems for no reason.

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                • #9
                  Hello Dion,

                  Why type of NAS device is it? On top of the latest firmware, are there also drivers available you could try updating?

                  When performing two server connections and using a content comparison scan (crc, rules-based, or binary), we download the files to a temporary directory from both locations, and then compare it.
                  From your example, I assumed that both servers were on different NAS devices or computers. Are the left and right side pointing to different locations, or are they pointing to the same NAS device?
                  Aaron P Scooter Software

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                  • #10
                    It's a Thecus N4100Pro that has the issues. It is comparing to a Synology DS710.

                    Given the time that has passed since I first reported the problem, I've started using another comparison application which doesn't have this problem; so I've stopped trying to troubleshoot BC.

                    Like I said, it works fine on individual folders (in small bits) but a large-scale compare causes errors.

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                    • #11
                      Was this issue ever root caused or resolved?
                      I am hitting a similar problem when comparing a UNC folder (sharepoint shared docs) to a local folder (Win7).
                      Date/timestamp compare works fine, but CRC/binary compare fails.
                      Copying the exact UNC path to a Windows Explorer window, I am able to open and copy the file.
                      But BC (v3.3.10 b17762) cannot compare it to the local file:
                      Unable to compare <file>: Cannot open file "\\unc\path\to\file". The system cannot find the path specified

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                      • #12
                        Hello,

                        First, all 3.x updates are free for 3.x users. You can update to the latest 3.3.13 for any potential bug fixes.

                        How is Sharepoint configured to share the UNC path? The issue in this forum thread is specific to the NAS hardware/driver configuration. The error message itself is a bit generic, handed back to us by the Copy method we use (which, is Windows provided). Normally, we expect that if Explorer works, we should be able to work, too, but sometimes Explorer is tested against/worked around while the core copy method does not work.

                        BC4 Pro adds the ability to connect directly to WebDAV, which one reason for adding was to help connect to Sharepoint.
                        Aaron P Scooter Software

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                        • #13
                          Looks like this is working fine now with 3.3.13.
                          Thanks.

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