The Geek Diary

Archives for September 2019

How To Disable Or Extend System Logging Rate-limit on CentOS/RHEL 6

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CentOS/RHEL usually uses rsyslogd rate-limit mechanism. Below is an example of message logged in /var/log/messages due to rsyslog rate-limiting. Feb 9 10:22:32 localhost rsyslogd: imuxsock lost 432 messages from pid 9832 due to rate-limiting Feb 9 10:22:45 localhost rsyslogd: imuxsock begins to drop messages from pid 9832 due to rate-limiting The rate limitation prevents logging […]

How To Disable Or Extend System Logging Rate-limit on CentOS/RHEL 7

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CentOS/RHEL usually uses rsyslogd rate-limit mechanism. However, CentOS/RHEL 7.x comes with systemd journal integrated to provide the ability to import structured log messages from systemd journal to syslog. The journal messages on the system’s /var/log/messages file looks like in the following example: Jul 30 03:29:45 hostname rsyslogd: imjournal: 102776 messages lost due to rate-limiting How […]

How to Configure a Fiber-Channel Over Ethernet (FCoE) Interface in CentOS/RHEL

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The Setup This configuration uses below OS, Storage and Server Hardware – OS release – “RHEL 7.1” Kernel – 3.8.13-55.1.6.el7.x86_64 Hardware: HP ProLiant BL460c Gen8 Ethernet Interfaces with FCoE capability – 04:00.0 Ethernet controller: Broadcom Corporation BCM57840 NetXtreme II 10/20-Gigabit Ethernet (rev 11) 04:00.1 Ethernet controller: Broadcom Corporation BCM57840 NetXtreme II 10/20-Gigabit Ethernet (rev 11) […]

How to Configure Early-kdump Support Feature in CentOS/RHEL 8

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What is early kdump support? In previous versions of CentOS/RHEL (5/6/7), the kdump service would start very late in the boot sequence. So early crashes information is lost during the booting. Starting CentOS/RHEL 8, a new kdump mechanism called “early kdump support” was introduced to tackle this issue. Early Kdump stores the vmlinuz and initramfs […]

How to check rpm package integrity in Linux

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Sometimes, after we download an rpm package manually, would need to check the package integrity sha1 (md5) or signature to avoid problems once it’s installed or during the installation. Also, we may need to find other package information like vendor, description, summary. This post describes ways to check rpm package integrity as well as package […]

How to Restart Network Services in CentOS/RHEL 8

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In CentOS/RHEL 8 the network services scripts are not presented anymore(systemctl start network.service or /etc/init.d/network script). In order to restart the network services follow one of these two options. Using Network Manager Use the systemctl command to restart the NetworkManager service/target as shown below: # systemctl restart NetworkManager Using nmcli Tool Note: Run these commands […]

How to Configure Nagios NRPE Client for System Monitoring (CentOS/RHEL)

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Question: How to configure CentOS/RHEL system as Nagios NRPE Client so it can be monitored from Nagios-Server for system health/performance? Enable EPEL REPO (Fedora Repository) and Install Required Packages 1. Download the epel repository packages for CentOS/RHEL 5 and 6. FOR CentOS/RHEL 6: # wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm For CentOS/RHEL 5: # wget http://dl.fedoraproject.org/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm 2. Install Epel […]

How to Set “dev_loss_tmo” Value Persistently Using Udev Rule

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1. Check the attributes of the FC remote port(s) using the below command: # udevadm info –attribute-walk –path=/sys/class/fc_remote_ports/rport-x:y-z 2. Then create udev rules that match all viable rports by matching the ‘role’ mentioned in the attributes returned in the above command. For example, create /etc/udev/rules.d/99-tmo.rules and include the below contents. ACTION!=”add|change”, GOTO=”tmo_end” KERNELS==”rport-?*”, SUBSYSTEM==”XXXX”, ATTR{roles}==”XXXX”, […]