System with a lot of SFTP connections becomes unresponsive, sluggish and eventually needs to be rebooted.

This document (7021112) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 12 Service Pack 2 (SLES 12 SP2)
SUSE Linux Enterprise Server 12 Service Pack 1 (SLES 12 SP1)

Situation

SAP Process Integration (PI) is running and checking a SLES 12 server for the existence of files via SFTP. After a while the server becomes very sluggish and PI has trouble creating connections to the SLES server.

Other symptoms of this are that other communication services are also slow or non responsive. Sudo takes a long time to return. Unable to create SSH connection.

If the server is rebooted it works fine for a while and then slowly reaches the state again where it can not do anything.

Looking at the support config and the SSH.TXT file it shows us this;

# /bin/systemctl status sshd.service

● sshd.service - OpenSSH Daemon

Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: disabled)

Active: active (running) since Thu 2017-07-06 08:49:48 EDT; 1 weeks 4 days ago

Process: 7724 ExecStartPre=/usr/sbin/sshd-gen-keys-start (code=exited, status=0/SUCCESS)

Main PID: 7734 (sshd)

Tasks: 511 (limit: 512)

Resolution

We changed the "/etc/systemd/system.conf" file and uncommented the "#DefaultTasksMax=512" and then changed the default to "4096".

Then issued a "systemctl daemon-reload" to apply the change. Once this was done the system started working properly.

Cause

The SAP application was using more than the default allotted Tasks. Setting the value higher and monitoring the usage resolved the issue.

Additional Information

Disclaimer

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Document ID:7021112
Creation Date: 19-Jul-2017
Modified Date:03-Mar-2020
- SUSE Linux Enterprise Server
- SUSE Linux Enterprise Server for SAP Applications

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