SSIS: FTP task - concurrent connections

Question

I have created an SSIS package for downloading file from FTP server. When I debug the package, everything goes fine. But when I shedule the package as Job step, it sometimes fails to connect. The job is sheduled to repeat every 4 hours and in average every other run fails with Error: 0xC002918F - The Login request was denied.

The connection is anonymous and doesn't require password

I have tested it for a few hours now and found out some info:

• When tested in FileZilla, I found out that the server denies second connection trying to download a file. Setting maximal number of concurrent connections to 1 got it working in FileZilla
• FTP command in command line works fine. Maybe because it closes connection after every successful command
• In FTP connection manager, I didn't found the option to limit number of connections

I have no possibility to see the settings of the FTP server. What confuses me the most is the fact, that some sheduled tasks work fine and some fail. I haven't found any regularity in it.

What I have tried so far:

• Active/pasive mode
• Limiting retries in FTP connection manager to 1
• Shifting the shedule time, so it doesn't collide with any other (older) tasks trying to download from the server
• Setting the FTP task to ASCII mode (The server says to FileZilla, that it only accepts ASCII characters)

No luck so far. Still some attemps success and some not.

EDIT:

The FTP server is on Simatic device.

For this week, i kept shedule for every 1 hour and kept pinging the device every 30 seconds. Still some SSID attempts don't succeed and ping goes through every time :-/

Answer 1

I would replace the standard SSIS FTP Task with an Execute Process Task, and call WinSCP.

https://winscp.net/eng/docs/guide_automation

I've found WinSCP is much more reliable and flexible. You can pass it a command line built using expressions to cover all the functionality of the SSIS FTP task, and more.

Answer 2

I think you have to accept just using a workaround in this scenario, maybe set the SQL agent SSIS job step to retry after an X seconds delay (advanced tab of SQL job step). We do this a lot when connecting to flaky cloud API's with SSIS.

Or maybe a for loop container in your package which continues on failure & breaks out on success - maybe try 3 times to connect?

Sorry if this is all obvious to you already.