I have pure-ftp on an OES 2 SP1 Linux server.
The home directory of the ftp user is set to an NSS volume /media/fs/DATA/home/user
When I connect to the ftp (FileZila) everything is ok.
When I copy a file from a workstation to the home folder then the file disappears from the home folder (in the NSS Volume) as soon as the upload end. Actually it becomes hidden (dot file not visible to ftp user).

When I ssh the server with root and go to the home folder of the ftp user I see a file named .pureftpd-upload.49ae80df.15.2537.a71fdfa3 .

/var/log/messages say:
pure-ftpd: (user@192) [ERROR] Rename/move failure: Invalid argument
pure-ftpd: (user@192) [NOTICE] /media/fs/DATA/home/user//file.doc uploaded (3231232 bytes, 10917.51KB/sec)

ftp user is of course LUM enable and has full access to its home directory.
Default Posix rights to uploaded files are 666.

Must be a kind of rights issue...?? it seems pure-ftpd is not able to rename the uploaded file to its real name.

I have the same configuration on another server. The only difference is that the other server does not have NSS, just ext3 and NCP and it works well.