Uncategorized – Page 29

100 Watt USB Power Monitoring

A couple of months ago, I discovered a USB Power Delivery (PD) cable that came with a little LCD display, so one could actually see the amount of power delivered over the cable. In the meantime, I’ve bought a couple of them because this is very useful. But they only show the power, no voltage and no overall power consumption over time. Also, I can’t measure power delivered by older power supplies with a USB-A connector or over USB PD cables that are permanently attached to a power supply. But I recently discovered a USB-C to USB-C USB PD tester with a small display that can do all of this: The JC-TC66C for around 35 euros.

LTE 5-Carrier Aggregation

I just had a look in my archive when I first started to see carrier aggregation in LTE networks. It turned out that, from my point of view, first networks and devices started to support the aggregation of 2 carriers with a maximum bandwidth of 2x 20 MHz in 2014. A few years later in 2016, high end devices began to support the aggregation of up to 3 carriers. Since then, network operators have have continued to increase the amount of spectrum they use in dense urban deployments, and mobile device hardware has further improved as well. Hence, I recently had another look at the state of the art.

Using the Smartphone Charger for the Notebook

Back in November 2021, I wrote a post on how current Power Delivery (PD) capable notebook chargers with a USB-C connector can be used to charge pretty much all other devices that are charged over USB. This is because USB PD is backwards compatible and also delivers power to devices that use USB power for charging. A couple of days ago I noticed that the reverse is also possible: Small and very lightweight USB PD capable chargers delivered with high end smartphones these days can also charge my notebook!

Bare Metal Cloud – Part 5 – Performance Comparison to Virtual Machines

One of the advertised advantages of renting bare metal servers in the cloud compared to using virtual machines on dedicated or shared hardware is their better performance. That sounds right but how much faster is an entry level bare metal server in a data center with a few CPU cores compared to virtual machines running on servers with high CPU core counts?

Bare Metal Cloud – Part 4 – Getting a Serial Console When the Network is Broken

When you are working with virtual machines in the cloud, I’m sure you’ve come across a situation in which you thought you had a great idea to reconfigure the network stack and ended up with the VM not being reachable anymore. As a last resort, one can always turn to the virtual machine manager and open a virtual display and log-in. When it comes to KVMs Virtual Machine Manager GUI, however, the display functionality is quite rudimentary, one can’t even copy/paste text to and from it. Especially when making larger changes on a config file, that’s quite a showstopper. But there’s another way: A virtual serial console!

Bare Metal Cloud – Part 3 – Several Public IPs – Macvtap vs. Bridging

In the previous post on the topic, I’ve had a look at how several virtual machines on my bare metal cloud server in a data center can share a single public IPv4 address. Public IPv4 addresses are expensive these days, so in many cases, sharing an IPv4 address and using non-standard ports for web servers and other things is hence quite acceptable. This is also how I run my main cloud server behind a DSL line with a single public IPv4 address. Nevertheless, for some applications, the use of standard TCP ports is a must.

As I have a lot of spare capacity on my cloud server, I’m thinking about migrating a number of services such as my BBB server, my Jitsi server, and several containerized web applications in virtual machines to VMs on the bare metal server. For these, I’d prefer to have individual public IPv4 addresses and no NAT in front of them. Turns out, this much easier to set-up than most configuration guides suggest.

Bare Metal Cloud – Part 2 – KVM and NAT Port Forwarding

Building on the previous post on this topic, I will have a closer look today how to use my new and shiny bare metal server in the data center for some virtual machine fun. As the server acts as a warm standby fallback for my cloud server at home, I’ve decided to use a setup that is as close as possible to main setup. Giving Proxmox a go would certainly have been interesting, but it’s only a single server and I would have strayed too far away from my already existing setup. So I decided to go for KVM/Qemu, as it is straight forward to set-up. Also, I could just use copies of my already existing virtual machines by modifying their configurations slightly, as they will obviously run in a different IP subnet. And this is where it starts to become interesting.

Bare Metal in the Cloud – Part 1 – Let’s Rent Hardware

So far, the public cloud has pretty much been ‘virtual machines’ for me, with varying numbers of CPUs, memory and storage, depending on the application. Recently, however, I’ve been looking for a way run copies of my home cloud based virtual machines (VMs) and Docker containers in a data center for redundancy purposes. For this purpose, renting separate VMs would be too expensive and inflexible. So, I decided to rent a ‘bare metal’ server in the cloud, and build a redundant copy of my cloud at home on top of it. This is what is referred to as a hybrid cloud, and this blog series takes a closer look at my adventures in this area.

Ubuntu 22.04 and x11 Remote Desktop Sharing

In the previous post, I’ve been looking at how Ubuntu’s built-in remote desktop sharing works and performs when the, by now, default Wayland display server is used. While the functionality was broken in my daily build of 22.04 (which is not yet released), it was working as designed in Ubuntu 21.10, so I gave it a try there. While Wayland remote desktop sharing in Ubuntu works in principle, it’s not usable over slow Internet connections. So I had a closer look if my standard solution with x11vnc still works in Ubuntu 22.04 when switching from Wayland to the tried and tested x11 display server.

Wayland, Remote Desktop Sharing and Ubuntu 22.04

Desktop sharing is one of the essential things I do every day. For almost 10 years now, I’m using x11vnc to get GUI access on remote Ubuntu desktops. There are many VNC servers, but x11vnc is the best I have found so far, as it works well even under extremely severe bandwidth constraints, i.e., it can easily live with 1 Mbit/s in the uplink when using the highest compression scheme. And if nothing happens on the desktop, there is almost no data transmitted. As the name implies, x11vnc is based on the x11 display server. That’s a bit of a problem these days, as all Linux distributions that use the Gnome desktop, including Ubuntu, are trying very hard for years now to switch to the newer Wayland display server. One of the problems that have plagued all attempts so far was the lack of a usable remote desktop solution. But now, it looks like Ubuntu will make Wayland the default compositor in the upcoming 22.04 Long Term Support (LTS) version. X11 is still supported, but once Wayland becomes the default, I wonder how much love x11 will still get!? So long story short, I was wondering what kind of remote desktop sharing solution Gnome and Ubuntu are proposing for 22.04 and whether it works as well as x11vnc. The answer was not as bad as I thought, but also not as good as I hoped.