Delay when writing to a file through pNFS

Delay when writing to a file through pNFS

[Jiri Kortus]

Hi,

I'm running a three-machine pNFS setup (MDS, DS and client on different 
virtual machines). When copying a file a mounted pNFS export or writing 
to a new file (with dd, for example), the write is delayed by 
approximately 15 seconds. When I write to a file that already exists, it 
works OK (there's no delay).

The NFS debug messages in kernel log (on the client) are showing that 
the client tries to write to the file, gets error -11 EAGAIN, waits 15 
seconds, then tries again successfully. I put a part of the kernel log 
concerning copying a small file to a pNFS export at 
http://charon.styxx.cz/tmp/pnfs/pnfs_write_log.txt

I have no idea what is the cause of the delays, so I hope someone could 
give me some advice concerning that. Thanks in advance.

Best regards,

Jiri Kortus