lftp over sftp > data corruption?

I've got an issue with data transfers using lftp over sftp.

I have a remote CentOS server on which I run Transmission (torrent client). Then I retrieve downloaded torrents from the server to some clients at home (mainly running Ubuntu).

The data transfer is made with sftp, using lftp as client and the "mirror -c" command.

The problem is that some data corruption occurs with that solution (I estimate about 1% of data).

What I do to check that: 1) I check the remote file on CentOS with the integrated "verify" command of the Torrent client 2) Files are verified 100% OK 3) I initiate lftp transfer on clients at home. 4) When mirroring is complete, I recheck all the files locally on Ubuntu machines with same torrent client, and files appear to be corrupted (usually missing about 2% to 0,5% of data).

As the issue seems to occur randomly, not all the files are corrupted. For example, in a group of "little" files (let's say 20 files 250Mb each), some files only will be corrupted (maybe 2 or 3). However, any "huge" file (let's say over 10GB) will certainly be corrupted at some point.

I would exclude: - Ram/HDD failure on server (as torrent verification on server always says files are 100% ok) - Ram/HDD failure on clients (I have this issue on 3 different kind of clients, with verified hardware and working clueless for anything else than lftp transfers).

So I can I troubleshoot this issue effectively?

Thanks.

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