Wu's Blog

Tag: Hardware

  • UCS Manager UI Fonts Size on 4K Screen

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    Older UCS Manager uses Java application. The UI fonts could be extremely small on high DPI screen. The fix is: Go to “C:Program Files (x86)Javajre1.8.0_171bin“. Go to “Properties” of “jp2launcher.exe“. “Compatibility” tab -> “Change high DPI settings“. Check “Override high DPI scaling behavior….“. Select “System (Enhanced)” or “System“.  

  • Troubleshooting Network Performance of Virtual Machine

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    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…

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

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    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…

  • Maximum Supported Boot Devices in Virtual Machine BIOS

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    Noticed a interesting limitation on VMware virtual machines. If you configure multiple SCSI controllers and distribute more than  8 virtual  disks. You may experience randomly OS boot up failure when power cycle VMs. Only last 8 disks with higher SCSI ID present in boot order settings of BIOS. You cannot choose the disks with lower…

  • Memory Errors on Modern Servers

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    I used to see memory degrading on  Cisco  UCS blades. But less see on HPE blades. I thought it maybe quality control problem of Cisco manufacture. Today I read two articles in Cisco website, it explains why we see memory degrading and how it works. I attached the articles below. Managing Correctable Memory Errors on…

  • Oracle Utilizes 50% of Physical Processors on HPE Server

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    DBA team told me Oracle was running slow on a HPE server. I observed the CPU utilization was about 50% of overall capacity. Whenever Oracle database bumps up the system experienced slowness. Further  digged into the issue, I see Oracle workload only ran on single physical processor, but the server has two processors. And the …

  • “No host data available” Reported in Hardware Status Tab

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    Just noticed a issue that nothing reported in ‘Hardware Status‘ tab of ESXi hosts in vSphere Web Client. KB 2112847 gives a solution but not works for me. The feature can be used to monitor hardware failures. I figured out a way to workaround it. You just need to login by Administrator account and click…

  • Cisco UCS blade B200 M4 discovery pending on 58%

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    New B200 M4 blades can running on Intel v4 processors. You may see discovery issue if your UCSM firmware version lower than 2.2.7c. I hit that problem few days ago when I install a new M4 blade. The FSM hung on 58% a real long time and failed eventually.

  • 在esxi主机上用LRDIMM还是RDIMM？

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    同事今天问了个关于ESXi内存的问题。硬件供应商有两种类型的内存，LRDIMM和RDIMM，应该选择哪一种？

  • LRDIMM or RDIMM on ESXi hosts?

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    Today my co-worker asked me a question about memory spec on ESXi hosts. There are two types of memory, LRDIMM and RDIMM available on hardware vendor’s list. Which one is best choice?