Categories
Hardware Windows

Fix: Flickering monitors on Lenovo P15

I am currently using a Lenovo P15 laptop, the machine itself is very powerful but has a very annoying isse. When using external monitors, either via docking or directly connected. They will often flicker/disconnect around once per minute. Causing everything to jump around until Windows settles down again. In some cases, the monitors even have to be disconnected and reconnected again before Windows can use them again.

Luckily, this issue can be solved rather easily. In Windows services, find the service named “FirmwareSwitchService”, stop & disable it. If you lack admin permissions, ask your IT department to help you. As there are currently no other ways around this issue on P15 models.

Categories
Linux Windows

How to install Raspian for Raspberry Pi from Windows

I am currently in the process of setting up a SETI@Home cluster running on Raspberry PI boxes. Currently i am working with three nodes, and i will expand it if is a success.

For OS, i use Raspian (Debian clone), combined with some cheap 8GB SDCards from a random cheap vendor.

In order to install the Raspian ISO image to a SD card, i use the application win32 disk imager, which simply takes a ISO image, and writes it to a designaded SD card.

It is worth noticing that this will cause the partition(s) on the SD card to not be any larger than the image itself. But you can fix this upon your first Raspberry PI boot, as the application “raspi-config” will be auto-started. (if not, start it)

Categories
Windows

Adding custom shortcuts to the Windows 8 start page

It is rather simple to add items to the metro home screen, by searching them up and then pinning them. But it is also possible to pin custom shortcuts to the same screen. Simply right-click the shortcut you want to pin, and select “pin to start”. It will then appear together with the other pinned content 🙂

Categories
Windows

Outdated entry in the DNS cache error when using Remote Desktop

You may sometimes get error messages about outdated entries in the DNS cache, when you are using remote desktop. (The connection cannot be completed because the remote computer that was reached is not the one you specified. This could be caused by an outdated entry in the DNS cache. Try using the IP address of the computer instead of the name.)

The first thing you should do, is to make sure that the clock is correct on these nodes:
1: The client machine
2: The remote machine you are connecting to
3: And if used, the domain controller(s).

And of course, make sure that you don’t have any invalid dns cache. clear the dns cache by doing this in cmd: ipconfig /flushdns.

If it is still an issue, another work around can be found here: http://extremeengineers.net/?p=126 (although, you should fix the problem and not the symptom)

 

Categories
Hardware Linux Windows

KVM: Optimizing performance on virtual machines (VM`s)

After having set up quite a few VM`s in my career, i have picked up a couple of tips on how to get the most power out of your VM`s:

Get new/correct drivers for your VM`s
Remember to make sure that you have all the correct drivers, this is at least important for IO(Disk) and Network devices. Windows has many devices that will work with basic Microsoft drivers, but that does not mean that the performance magically gets awesome. After making sure that the correct drivers were in place, i managed to go from ~900Mbit to 9.9Gbit on a 10gbit-network between a Linux (Red Hat) and Windows 2k8 server. (tested with iperf which exists for both Windows and Linux)

Turn off Power saving options in BIOS / Hardware
More or less all servers, either they being brick servers, home servers or blade servers, have BIOS settings that enables or disables power saving mode. I know from experience that at least all HP blades comes with power saving enabled per default. Turn off this to make sure that your VM`s gets the performance they expect to get. (I have had VM`s simply be sluggish with this feature turned on, turning it off made CPU-performance get normal)

Turn off CPU throttling on the VM host machine
I have also had issues with slow VM`s even when the power options was fixed in BIOS. I then realized that some Linux distributions (Ubuntu) have a default CPU scheduler that throttles down the CPU when it is not needed. After making sure that the host did NOT do this, the VM`s finally started acting as they should. Check out your Linux distributions guides on how to change this.

 

Any other tips i should add to the list? Feel free to add a comment below! 🙂