Hardware

Cisco UCS Blade Cannot Get IP Address for KVM

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You may see “The IP address to reach the server is not set” when clicking the KVM console in Cisco UCS Manager. The issue persists even Cisco UCS Manager has enough IP addresses for management. Re-acknowledge or reset CIMC cannot fix the problem. The fix procedure is go to “Equipment” -> Select the server -> … Read more

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 … Read more

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 … Read more

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 … Read more

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 … Read more

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  … Read more