[Nbd] question about i/o scheduling

[Peter Simons <simons@...813...>]

Hi guys,

first of all, thanks a lot for the effort you're putting into nbd. The
package has handled my off-site backups gracefully for 2+ years, so I am
one happy user!

Now, it looks to me like my kernel performs too much write-buffering.
When a large file is copied to an nbd-mounted partition, the initial 2
MB or so are transferred at incredible speed; apparently, because the
kernel just buffers the data. At one point, the kernel actually tries to
transfer the data to the remote host, but that takes several minutes.
During that time, the nbd-device is almost unusable for other processes
because it accepts no more writes at all (and reads have a hard time
getting through the network connection).

Has anyone else observed that phenomenon? Is there maybe a way to
improve the situation?

Take care,
Peter