MFC: r269788

Document the use of the vfs.nfsd sysctls that control the size of
the NFS server's DRC for TCP.
This is a content change.

1 files changed, 19 insertions, 1 deletions

diff --git a/usr.sbin/nfsd/nfsd.8 b/usr.sbin/nfsd/nfsd.8
index d865d7e..660e5e8 100644
--- a/usr.sbin/nfsd/nfsd.8
+++ b/usr.sbin/nfsd/nfsd.8
@@ -28,7 +28,7 @@
 .\"	@(#)nfsd.8	8.4 (Berkeley) 3/29/95
 .\" $FreeBSD$
 .\"
-.Dd July 18, 2014
+.Dd August 10, 2014
 .Dt NFSD 8
 .Os
 .Sh NAME
@@ -175,6 +175,24 @@ utility
 would then be used to block nfs-related packets that come in on the outside
 interface.
 .Pp
+If the server has stopped servicing clients and has generated a console message
+like
+.Dq Li "nfsd server cache flooded..." ,
+the value for vfs.nfsd.tcphighwater needs to be increased.
+This should allow the server to again handle requests without a reboot.
+Also, you may want to consider decreasing the value for
+vfs.nfsd.tcpcachetimeo to several minutes (in seconds) instead of 12 hours
+when this occurs.
+.Pp
+Unfortunately making vfs.nfsd.tcphighwater too large can result in the mbuf
+limit being reached, as indicated by a console message
+like
+.Dq Li "kern.ipc.nmbufs limit reached" .
+If you cannot find values of the above
+.Nm sysctl
+values that work, you can disable the DRC cache for TCP by setting
+vfs.nfsd.cachetcp to 0.
+.Pp
 The
 .Nm
 utility has to be terminated with