On Wed, Jun 09, 2021 at 06:19:43PM -0700, L A Walsh wrote: > I've been using a character device on linux in my > home directory named 'zero' that is a copy of the > 'zero' device in /dev: > crwxrwxrw- 1 1, 5 Jun 15 2015 zero > > to do read benchmarks using 'dd' (and write benchmarks > using a file named 'null' thats a copy of /dev/null). > > I run it "occasionally", but not on a regular basis, since > it stays a bit boring. Nevertheless, ballpark numbers > consistent with historical norms verify correct network > function (separate from read/write files). Read/write speeds > at last check a few weeks ago were typical with > reads at 700MB/s and writes at about 300MB/s. > > A few hours ago I tried it again due to some strange network > probs where I seemed to be getting file xfer speeds as low > as 200K/s. > > I tried the bench script, and its half broken now -- because > I can no longer get anything back from the zero device > on my server via the network. Locally, I can do 'dd' from > /dev/zero (or the zero file) and it takes a few seconds and > gave about 800MB/s. So seemed to have been working fine, > but remotely -- still nada... reads 0 bytes from /dev/zero > and about 300MB/s write speed. > > Can anyone think of anything that might have changed in > cygwin such that it would know the remote device is a > "/dev/zero". Wondered if the 'dd' prog might have changed, > but just realize it did same with 'cat' as well. > > Anyway -- I'm a bit stumped as to possible causes... > The writing to a remote /dev/null part is still working, > so not sure why one would change and not the other. > > If anyone can think of anything, please let me know -- I'm > also gonna ping the samba list and maybe my distro list > > Thanks! > -linda > nfs / nodev?
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