How to shrink an LVM Logical Volume

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 …

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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 …

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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 …

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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 …

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