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FTP of very large file to Windows Server does not complete totally

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  • FTP of very large file to Windows Server does not complete totally

    Hello, I'm a new user to your Forums but have worked with AS/400 (iSeries) since the very beginning.

    I wrote a 'remote daily backup' that does what the IBM daily backup does (save all libraries, all DLOs, all remaining IFS, security, and configuration) but sends each save file over the internet to our company's backup server. This has worked well for smaller systems, but I have a customer with a very large library, approx. 2.4gb, whose save file PUT never fully completes. Although the file appears to be complete on our backup server, the FTP dialog on the iSeries never shows the '226 Transfer Complete' message. Instead, the message 'No response from host; all connections closed' message is issued. I am disabling Extended Passive Mode and using the default Passive Mode. I tried changing the timeout values using the DEBUG T1 and DEBUG T2 commands, but this did not help; in fact, caused long timeouts between PUTs. The iSeries is on V6R1; the backup server is Win 2008 R2.

    Any ideas would be helpful.

    Thanks!

  • #2
    Re: FTP of very large file to Windows Server does not complete totally

    perhaps its the keep alive timeout within tcp on the iseries.
    Hunting down the future ms. Ex DeadManWalks. *certain restrictions apply

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    • #3
      Re: FTP of very large file to Windows Server does not complete totally

      I'd guess that one system or the other uses 32-bit integers to keep track of sizes. Signed 32-bit integers store a maxmum value of 2.1 billion, so when you reach that value, they fail. That's just a guess, of course.

      I can't see what this could possibly have to do with keep alives?!

      I would not recommend using FTP for this, at any rate. At least, not unless you have FTP clients/servers that support resuming a failed transfer. (Which exist, but aren't that commonplace.) Communications can fail, and for smaller files this isn't a big deal, you just re-send them. But for large files, resending can be a big deal. Using a file transfer method that allows interrupted transfers to be resumed is a must for that sort of thing.

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      • #4
        Re: FTP of very large file to Windows Server does not complete totally

        Scott,

        You are correct; FTP does not support recovery of a failed transfer. What other means are available to programmatically copy files from the iSeries to a share on a Windows server?

        Thanks,

        Mark

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        • #5
          Re: FTP of very large file to Windows Server does not complete totally

          Originally posted by markrmiller View Post
          You are correct; FTP does not support recovery of a failed transfer.
          Not exactly true, the FTP standard (defined in RFC 959) does allow for a REST (Restart) command that lets you resume a failed transfer. The trouble is, you have to make sure you have an FTP client and server that support this command or it won't work. So you shouldn't say "FTP" (in the general sense) "does not support recovery . . ."... however, you can say "The FTP client that IBM provides with the IBM i operating system does nto support recovery . . ."

          Originally posted by markrmiller View Post
          What other means are available to programmatically copy files from the iSeries to a share on a Windows server?
          There are many thousands of ways... off the top of my head, I can't think of one with restart capabilities. Simply breaking the files up with a tool like "rar" might be one way, though. Then you only have to resend the last file you were working on.

          Not sure if that's helpful, sorry.

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