Current setup:
Windows 2003 server machine has a CIFS/SMB share sharing something like C:\ = //windowshost/C is being shared.

Other Linux machines are mounting this share like so:
//windowshost/C on /mnt/windowshost/C type cifs (rw,mand)

Most of the time i am able to browse, copy, edit files through the mount but occasionally I will get the following error when copying files to the mount:
cp: accessing `/mnt/windowshost/C/some/path/here/': Resource temporarily unavailable

The thing is, an automated python script is copying files and sometimes getting this resource error, when i manually browse the mount its fine. The mount is also not heavily used, each Linux host is probably copying a 100KB file once every 3-4 minutes, and there are about 3 hosts.

The windows machine has not been down and no network outtages. Any known issues to "Resource temporarily unavailable" errors? The Windows box is 2003 so its probably using SMB 1.0

Thanks in advance for any support!

According to the fcntl man page, you get EAGAIN when you attempt a nonblocking operation on a filesystem mounted with mandatory locking. Why are you setting the mand option? The default is advisory. Your other browsing is likely to open the files without setting O_NONBLOCK, so is not causing a problem.

When I mount with -t cifs, it gives me RW, MAND by default. I tried giving it the option nomand, but it looks like it ignores it and still defaults to MAND.