Subject: NFS problems and solutions
To: None <>
From: Robert Dobbs <>
List: current-users
Date: 12/14/1994 23:27:37
Situation: Machine A with old ethernet card (3c503) produces "reciever ring
buffer overrun" some of the time due to (what I assumed to be) packets 
arriving before other packets were cleared from its buffer.  Access of 
files via NFS client or server would lock up if the files were larger than

Reality: 8192K packets were being used by NFS and as they were too big for
machine A's buffer, they would be instantly dropped and caught in a loop
of resubmission/dropping.  "ring buffer" implies either a loaded net or
packets too large.

Solution: Mount filesystems with -is and -R5 so you can ^C out of locked
up NFS transfers, and limit the number of retries.

Use the -r and -w flags to limit the size of NFS packets (4096 works in my

Define NFS_BOOT_RWSIZE=8192 when compiling a kernel, this will allow NFS to 
step down the transmit size when things aren't working.  It starts at that
size and steps down; so I could set NFS_BOOT_RWSIZE=4096 to make certain my
transfers would always work the first time (but I have other NFS mounts that
I'd like to run at 8K)


Is there a reason this last isn't defined by default?