We are using the SecureFileTransferClient class to send files to various FTP servers. We came across an instance where using edtFTPj FTP is roughly 10 times slower than a transfer executed by the native OS's FTP client.
We are running the clients on AIX 7.1 and transferring to another AIX 7.1 FTP server. There are no hops between the servers. Both transfers are done using passive mode. Active mode is strangely 3 times slower than passive mode for the edt client where as active and passive mode have similar rates when using the AIX FTP client. The rate for the edt client in passive mode is strangely capped at around 7MB/sec.
We've another AIX 7.1 server to test a transfer to, however, the transfer rates for AIX vs edt are comprable (fast) and don't appear capped. We compared network card settings between the two and the buffers on the slower setup are small than the buffers in the faster setup. MTU for each setup is 1500. There aren't any other OS-related rate governors enabled.
The edt buffers are not modified from their default settings. We are on version 4.7.0 running on Java 7. We have a debugging trace turned on to examine the FTP server interactions and edt client settings.
We've not sure of what to look at next in terms of comparing the two systems. Is there any setting in the edt library we can examine or tweak that could give us a hint at what to look at next? Any other techniques for resolving transfer rate differences?