Sunrpc settings are not persistent after reboot.

This document (7022831) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server 12

Situation

SUNRPC tunables in /etc/sysctl.conf, such as "sunrpc.tcp_max_slot_table_entries" are not persistent after a reboot. 
However, they still can be set after boot-up by executing "sysctl -p" which will read the settings again from /etc/sysctl.conf.

After such a boot, the following error can be found in /var/log/messages:

error systemd-sysctl[941]: Couldn't write '128' to 'sunrpc/tcp_max_slot_table_entries', ignoring: No such file or directory.

Resolution

The sunrpc module needs to load early in the boot process in order for sysctl.conf to set these items successfully.  In some configurations, sunrpc is not loaded until later.

There are several ways to address this issue, the easiest two methods are:

1.  Update nfs-utils, which will cause the sunrpc module to load earlier in the boot process.

On SLES 15 SP3 and SP4, update to nfs-utils-2.1.1-150100.10.27.1.

On SLES 12 SP5, update to nfs-utils-1.3.0-34.37.3.

2.  Even without the updates mentioned in #1 above, if either nfs.service or nfsserver.service are enabled, sunrpc will load earlier in the boot process.  For example, executing the following command will address the issue:

systemctl enable nfs.service

Note:  nfs.service is merely a set of checks to make sure everything is present which is needed for the NFS Client to successfully mount NFS shares.  Many NFS mounts can succeed without this, but for best NFS client functionality, it should be enabled.  Enabling this is safe even if no NFS mounts are expected to be performed.

Cause

In some configurations, the sunrpc kernel module is not loaded before systemd-sysctl service is started.

Additional Information

Potential sunrpc settings that can be set in /etc/sysctl.conf
sunrpc.max_resvport = 1023
sunrpc.min_resvport = 665
sunrpc.nfs_debug = 0x0000
sunrpc.nfsd_debug = 0x0000
sunrpc.nlm_debug = 0x0000
sunrpc.rpc_debug = 0x0000
sunrpc.tcp_fin_timeout = 15
sunrpc.tcp_max_slot_table_entries = 65536
sunrpc.tcp_slot_table_entries = 2
sunrpc.transports = tcp 1048576
sunrpc.transports = udp 32768
sunrpc.transports = tcp-bc 1048576
sunrpc.udp_slot_table_entries = 16

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7022831
  • Creation Date: 10-Apr-2018
  • Modified Date:09-Jan-2023
    • SUSE Linux Enterprise Server

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