[CentOS] Kerberized NFS client and slow user write performance

Matt Garman
2016-10-07T16:40:11Z

We seem to be increasingly hit by this bug:

https://access.redhat.com/solutions/2040223
"On RHEL 6 NFS client usring kerberos (krb5), one user experiences
slow write performance, another does not"

You need a RH subscription to see that in its entirety.  But the
subject basically says it all: randomly, one or more users will be
subjected to *terrible* NFS write performance that persists until
reboot.

There is a root cause shown, but that is cryptic to non-kernel devs;
it doesn't explain from a user perspective what triggers this state.
(That's why it appears to be random to me.)

There is no solution or workaround given.  This appears to be on a
per-user + per-server basis, so a crude workaround is to migrate the
user to a different server.  And we do regular reboots, which somewhat
hides the problem.

My question to the list: has anyone else dealt with this?  The link
says "Solution in Progress", but that was last updated nearly a year
ago.  We don't have any support contracts with upstream, just the
website access subscription, so I doubt RH will offer any help.
Appreciate any suggestions!

Thanks,
Matt