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Showing posts from January, 2018

Troubleshooting Network Performance of Virtual Machine

There are several layers of networking on the virtualization infrastructure. Guest operating system, Virtual Machine, ESXi driver, physical network adapters, RJ45/SFP and network switches...etc. Sometimes it's hard to say where exactly caused a problem. Especially hardware layer problems. Today I worked on a very interesting case, it may give some ideas to troubleshooting network performance issue which is caused by hardware layers. A user told me he was bothered by network performance of a virtual machine. It's slow to copy data to NFS share. But responding to "ping" command looked good. I didn't see any issue on virtual machine layer. VMware Tools was up to date, Windows OS was patched, virtual network adapter type was VMXNET3 and VM version was also up to date. When I tried to copy an image file to share folder of the virtual machine, I did see sometimes speed was fast, but sometimes not. Since I have two physical uplinks, it led me to guess it could be one of

IE 11 Window Doesn't Change Between 4K Internal and Regular External Monitors

Just a quick notes. If you use multiple monitors, some are 4K and some are regular resolution, you may see window display issue when move Internet Explorer between these monitors. Follow the KB below to change register to allow Internet Explorer 11 accommodates the monitor solutions. Internet Explorer 11 window display changes between a built-in device monitor and an external monitor

The older version of cis-upgrade-runner cannot be removed when upgrade vCenter Server 6.0

When you upgrade or patch vCenter Server 6.0 for Windows, you may see following symptoms: "The older version of cis-upgrade-runner cannot be removed. Contact your technical support group." Or error code 1063: "Installation of component VMware CIS upgrade runner failed with error code '1063'" That means the vCenter Server installer cannot find MSI files of existing vCenter Server services. It could be following reasons: You delete MSI files in "Temp" folder of the profile you used to install vCenter Server. The account you used to login and install vCenter Server was roaming profile. The profile's "Temp" folder was automatically deleted when you reboot/logoff the server. vCenter Server 6.0 for Windows is consist of lot of standalone package. The upgrading process usually uninstall old packages, and then install newer packages. So the failure doesn't impact to database or inventory data. You can re-initiate the upgrading again.

CVE-2017-5754, CVE-2017-5753 and CVE-2017-5715 (Spectre and Meltdown)

You may know there are 3 vulnerabilities recently noticed by industry. Long story to short, kernel address space exposed to hackers when processors running user space code. It's not only impact to Intel processors but also AMD and ARM. CVE-2017-5715 is a hardware issues that only apply certain firmware can fix the vulnerabilities. CVE-2017-5754 and CVE-2017-5753 need to apply OS patches to change how codes access kernel address space. Following are some useful links just for your reference. CVE-2017-5753 CVE-2017-5715 CVE-2017-5754 VMware: https://www.vmware.com/security/advisories/VMSA-2018-0002.html (For CVE-2017-5753 and CVE-2017-5715. VMware has not published anything for CVE-2017-5754 yet.) Microsoft: https://support.microsoft.com/en-gb/help/4072698/windows-server-guidance-to-protect-against-the-speculative-execution https://support.microsoft.com/en-gb/help/4073119/protect-against-speculative-execution-side-channel-vulnerabilities-in HPE: http://h22208.www2.hpe.com/eginfolib/