NFS server limiting the number of connections. Why?

[tgwena]

I have built myself a cluster of 20 Raspberry machines. I have set one of them to be an NFS server, and all the others are NFS clients (including the server, for uniformity).

The /etc/exports configuration file for the server (named rg.local) has the line

/home/pi *(rw,sync,no_subtree_check)

The /etc/fstab configuration files for the clients have the line

rg.local:/home/pi /mnt/g nfs defaults 0 0

I can get 15 of the clients to connect to the server, but trying to connect a 16th machine hangs. I have checked that it does not matter which 15 connect.

I have increased the number of initial threads to 20 in the file /etcdefault/nfs-kernel-server but this has been of no help.

I have been trying to figure out why this is happening and I am stumped.

Does anyone understand what is causing this? Is there some limit set by SystemD, to manage resources?

After some research I found this issue occurs only in NFSv4.

[DougieLawson]

What value do you have in /etc/default/nfs-kernel-server for

Code: Select all

# Number of servers to start up
RPCNFSDCOUNT=8

[tgwena]

What value do you have in /etc/default/nfs-kernel-server for

Code: Select all

# Number of servers to start up
RPCNFSDCOUNT=8

I put it up to 20.

[MarkJ62]

I’m having a similar issue. I have increased the limit to 20 as suggested by Dougie Lawson. I have 18 nodes that are listed by exportfs but I can’t seem to get past 15 connected.

If I pick one that hasn’t connected and manually issue the mount command it just sits there. Doing a ”netstat -a | grep nfs” on the nfs server shows it as having established a connection and some random port assignment, but the nfs client seems to hang. I’m running Stretch and the 4.14 kernel on all the nodes and nfs server.