Since shrinking is not supported on these file systems, you cannot reduce the size of a logical volume that houses a GFS2 or XFS file system. The lvreduce command typically warns about potential data loss and requests confirmation. In some circumstances, such as when the logical volume is inactive, or the —resizefs option is not …
How to change log files permissions in bind?
The umask settings are passed down from the parent process to the BIND process. This means that the permissions for all files made by BIND can be restricted. You need to change the systemd unit file so that “others” can’t read, write, or run any files made by BIND. Create a directory for drop-ins in …
How to increase number of open files limit in CentOS 5,6, and 7
When load testing an application and seeing “Resource temporarily unavailable” issues, increase the “nofile” and system-wide limitations for the number of open files. The kernel allows a certain amount of continuously open file descriptors. This number will automatically vary depending on the amount of RAM in the system by default. In the file /etc/sysctl.conf, edit/add …
rsync: Failed to exec ssh: Permission denied (13)
When another SELinux confined process starts rsync, it fails with the following error. rsync: Failed to exec ssh: Permission denied (13) The following error may appear in some cases. rsync: readlink_stat("/some_file" (in some_path)) failed: Permission denied (13) To resolve the above issue, turn on the following SELinux Booleans. rsync_client to allow rsync client to run …
Restore the /boot directory after corruption or missing files
Enable the network so yum can function. Mount /boot from your disk. #mount /dev/sda1 /boot Make a directory grub2 on /boot as follows. #mkdir /boot/grub2 Copy the modules as or copy the entire things from an identical system as fonts locale directive. #cp -r /usr/lib/grub/i386-pc /boot/grub2/i386-pc Reinstall the kernel packages # yum remove kernel-<release># yum …
How to assign alias IP addresses to a network card
In order to add an additional IP address to an interface, there are two options: Aliases, in the old way, generate a new virtual interface named ethX:Y, for example, eth0:1. Each interface has its own IP address. A label is applied to it in ifconfig output as well as ip output. In the new method, …
What does Ping mean?
Nothing is more aggravating than getting into a gaming groove with your pals only to have your frames per second (fps) drop and your game lag at any time during the session. You’re undoubtedly curious in what’s going on with your system or network behind the scenes, and if there’s anything you can do about …
How to add Equal Cost Multipath Route [ECMP] to IP Routing?
You can add ECMP routes with the following command. ip route add 172.16.0.0/24 nexthop via 10.0.1.1 dev ethX weight 1 nexthop via 10.0.2.1 dev ethY weight 1 Alternatively, you can use two separate commands, the second of which appends to the existing route. ip route add 172.16.0.0/24 nexthop via 10.0.1.1 dev ethX weight 1 ip …
HowTo wipe ceilometer in OpenStack
The following is performed on the overcloud controllers. First of all stop telemetry with the following command. systemctl stop openstack-aodh-evaluator openstack-aodh-listener openstack-aodh-notifier openstack-ceilometer-central openstack-ceilometer-collector openstack-ceilometer-notification openstack-gnocchi-metricd openstack-gnocchi-statsd Stop the mongod service. systemctl stop mongod Backup MongoDB files. tar Jcf /tmp/mongodb-backup-$HOSTNAME-$(date +%F_%H%M%S).tar.xz /var/lib/mongodb Delete the following files from the /var/lib/mongodb/ folder. rm -r /var/lib/mongodb/* Start mongodb …
How to set the route metric on network interface in CentOS 7
What is a Route Metric? In networking, the term metric is used to assign priority to network routes. The lower the metric, the lower the route’s priority. Set Route Metric Without Network Manager Under Red Hat Enterprise Linux, the correct way to set the route metric is to edit the appropriate <ifcfg-interface> file in the …