The Geek Diary

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", … [Read more...] about How to Set “dev_loss_tmo” Value Persistently Using Udev Rule

The Problem While executing: # yum update The following error occurs: One of the configured repositories failed (Unknown), and yum doesn't have enough cached data to continue. At this point the only safe thing yum can do is fail. There are a few ways to work "fix" this: 1. Contact the upstream for the repository and get them to fix the problem. 2. Reconfigure the baseurl/etc. for the repository, to point to a working upstream. This is most often useful if you are using a … [Read more...] about “Could not resolve proxy: https; Unknown error” – error with ‘yum update’

This post will guide the user on how to reinstall a corrupted library via yum. In general, the command below will find which package the corrupted library belongs to: # yum provides \*/[so_file] In this example, we used this error message "/bin/login: error while loading shared libraries: /lib64/libcrypt.so.1: file too short" to identify the corrupted library and the find the package it originally came from: # yum provides \*/libcrypt.so.1 ... glibc-2.17-260.0.17.el7_6.6.x86_64 : The … [Read more...] about How to Reinstall Corrupted Library with yum

The Task Create an LVM snapshot of the root filesystem. Revert Snapshot Changes To An Earlier State. The Solution 1. Before proceeding make sure LVM Volume Group (VG) has enough space for the snapshot. # vgs VG #PV #LV #SN Attr VSize VFree ol 2 2 0 wz--n- 12.00g 1.01g 2. In this example we are creating a root snapshot of 512M. Here "snap" is the snapshot name of a root volume. # lvcreate -L 512M -s -n snap /dev/ol/root Logical volume "snap" created. 3. … [Read more...] about How to Create An LVM Snapshot Of The Root Filesystem And Restore To An Earlier State

Below we demonstrate three common methods for transforming the iptables rules into the firewalld controls. Our example shows the transformation of one iptables rule output by the iptables-save command: LOG_TEST_NEW - [0:0] -A LOG_TEST_NEW -m limit --limit 2/min -j LOG --log-prefix "New Connection" The example rule logs up to two log entries per minute. The log entry is labeled with the string "New Connection." Using The firewalld GUI (Applications -> Sundry -> Firewall) 1. Create a Rule … [Read more...] about How to Migrate CentOS/RHEL 6 iptables Rules to CentOS/RHEL 7 firewalld

The Scenario The system is not configured to use the ntpd service to synchronize time and date. CentOS/RHEL 7 uses systemd to manage services. The timedatectl utility is distributed as part of the systemd, and allows you to review and change the configuration of the system clock: change the current date and time, set the time zone, or enable automatic synchronization of the system clock with a remote server. The NTP service is enabled, but as this system is running CentOS/RHEL 7, … [Read more...] about Time goes out of sync on a node running CentOS/RHEL 7