Generally, you will use virsh to control VMs, but there are a few useful functions you can get from xm but not virsh. We cover the most common commands here. How to list the currently running VM on physical server? # xm list Name ID Mem VCPUs State Time(s) 0004fb00000600004689b1d1cc6e83d9 1 1027 1 r—– 293.5 […]
RHV
KVM Virsh Command Examples on CentOS and RHEL
virsh is the interface or command for managing the virtual machines based on the KVM hypervisor. On virsh interface virtual machines are identified by their domain names, so virsh is generally used to list current domains, to create, pause & shutdown domains. Virsh comes under GNU Lesser General Public License and supports Xen, QEmu, KVM, […]
Difference Between Qemu and KVM
Qemu It is a generic and open-source machine emulator and virtualizer. When used as a machine emulator, QEMU can run OS and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC). By using dynamic translation, Qemu achieves very good performance. Some of the Important Features are mentioned […]
How to Increase KVM Guest vCPU Resources
This post illustrates the steps about how to increase KVM guest vCPU. There are two methods to increase KVM guest vCPUs: on the fly and offline. Let us see the steps for each of the method below. Increase KVM guest vCPUs online 1. Check the current KVM guest vcpu/memory on KVM host: [root@kvm-host]# virsh dumpxml […]
How to Increase KVM Guest Memory Resources
This post illustrates the steps about how to increase KVM guest memory. If the current KVM guest memory is the same as the memory limit, you can to increase the memory offline following the below steps: 1. Check the current memory status of the KVM guest: [root@kvm-host]# virsh dumpxml kvm-guest | grep -i memory <memory […]
How to Rename KVM VM with virsh
The syntax to rename a KVM VM with virsh is: # virsh domrename {domain} {new-name} 1. To rename VM from Production-A to Production-B, first shutdown the VM Production-A: # virsh shutdown Production-A 2. Now rename the VM, using below command: # virsh domrename Production-A Production-B Domain successfully renamed 3. Start the VM/domain, once the rename […]
How RHEVM Monitor Storage Health
This post will illustrate how RHEVM monitors storage health in detail. Monitor Storage Pool Manager Health The Storage Pool Manager (SPM) is a management role assigned to one of the hosts in a data center enabling it to manage the storage domains of the data center. RHEVM check SPM availability and metadata integrity at every […]
How does Sanlock Work in RedHat Virtualization
In RHV, KVM Host uses Sanlock to detect the connectivity with Storage domain. When Sanlock enables, it will open wdmd daemon(watchdog multiplexing daemon) and send keepalive with certain heartbeat. sanlock IO to storage does not complete within a fixed time, sanlock stop sending keepalive to wdmd. When it is timeout,the wdmd daemon controlling /dev/watchdog will […]
RHV – Understanding “Resilience Policy” for VM live migration
In RHV web portal, Select “Compute” -> “Cluster” -> Select one cluster object -> click “Edit” -> click “Migration Policy”, there is a control called “Resilience Policy”, this note explains how “Resilience Policy” controls VM live migration during an outage. Basically “Resilience Policy” controls how virtual machines running on the host in “Non-operational” state in […]
How To Change Engine Database Password for RHVM Engine
This post illustrates steps to change engine database password for RHVM engine. 1. Before modification, you can run below commands to check the current ENGINE_DB_PASSWORD for RHEVM engine interacting with the engine database. By default, ENGINE_DB_PASSWORD is a random string which is auto-generated by engine-config during the setup process. The ENGINE_DB_PASSWORD is used by below […]