Getting this output on your RHEL/CentOS virtual machine? Clocksource tsc unstable (delta = 000000000 ns). Enable clocksource failover by adding clocksource_failover kernel parameter. First find out the available clock sources : cat /sys/devices/system/clocksource/clocksource0/available_clocksource You will likely get the following results : kvm-clock tsc acpi_pm You are currently using “tsc” as per the initial output error, try… Read More »
I recently faced the following issue with VMware ESXi vSphere 5.5 hypervisor, trying to connect a USB device to a virtual machine. The host server was actually able to see the USB device : lsusb Bus 02 Device 04: ID 1058:0748 Western Digital Technologies, Inc. Bus 02 Device 03: ID 09eb:0131 IM Networks, Inc. Bus… Read More »
If after a power outage or ESX hypervisor shutdown your iSCSI datastores are missing, it might be caused by a lock on the LUN on your host machine. You may find this in your vmkernel logs : /var/log/vmkernel.log 2014-02-19T04:19:11.927Z cpu3:33477)NMP: nmp_ThrottleLogForDevice:2321: Cmd 0x88 (0x412e80814440, 0) to dev “t10.FreeBSD_iSCSI_Disk______74867ae04094000_________________” on path “vmhba37:C0:T1:L0” Failed: H:0x2 D:0x0 P:0x0 Possible… Read More »
It’s possible to tell the kernel of your Xen guest VM to synchronize or not the clock with the physical host machine. There are numerous reason why you would or not to use this feature (such as your guest VM is behind or forward the clock over time). To find out the current setting, simply… Read More »
VMware ESXi management IP/vSphere connectivity might become suddenly unavailable over the time or after replacing the network interface card. This can be easily resolved by removing the vmnic port groupe for the management network and add it back again to the vSwitch. You will need direct console access to the ESX shell to perform these… Read More »
Ending up with this kind of error booting a guest machine on your Xen hypervisor? Running: xm create /cloud/config/hjxmogr553e5jx Using config file “/cloud/config/hjxmogr553e5jx”. Error: Unable to connect to xend: No such file or directory. Is xend running? Fatal: Virtual machine has not been started on hypervisor Executing Rollback… The two possible causes would be the… Read More »
Oracle VirtualBox do not have such feature through the GUI. However, you can use the command line and the task scheduler to do so. First, you need to grab guest virtual machine ID that you want to be started in background. Open the command prompt, and change directory as followed : cd C:\Program Files\Oracle\VirtualBox\ Then… Read More »
Lost your root password? Well, this is very unfortunate! This tutorial will show you how to reset ESXi root password. There is no supported method to “reset” the root password, VMware suggest to boot from ESXi installer disk and select “Install ESXi, preserve VMFS datastore” option. This will overwrite the current installation (fresh install, overwriting… Read More »
If you get the following message booting a VMware guest machine : Your CPU does not support long mode. Use 32bit distribution. This mean Virtualization Technology is disabled in the BIOS. Simply enable VT and boot your VM again.
NTFS filesystem store a lot of information that might not be required all the time and can significantly improve the I/O performance when disabled, especially under a virtualized environment. To disable Last Access Time Stamp on Windows, you need to manually edit the registry. 1. Open the registry editor : Start > Run > regedit.exe 2.… Read More »