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Earlier this year, we released the public preview of the serial console feature of Azure Virtual Machines (VMs). Today we are announcing the general availability of serial console and we’ve added numerous features and enhanced performance to make serial console an even better tool for systems administrators, IT administrators, DevOps engineers, VM administrators, and systems engineers.
For those new to serial console, you’ll likely recognize this scenario: You’ve made a change to your VM that results in you being unable to connect to your VM through SSH or RDP. In the past, this would have left you pretty helpless. However, serial console enables you to interact with your VM directly through the VM’s serial port – in other words, it is independent of the current network state, or as I like to say, it’s “like plugging a keyboard into your VM.” This means that you can debug an otherwise unreachable VM to fix issues like a broken fstab or a misconfigured network interface, without needing to resort to deleting and recreating your VM.
The latest features for serial console include a subscription-level enable/disable feature, support for magic SysRq keys, support for non-maskable interrupts, accessibility improvements, and performance and stability improvements. Serial console can now be turned off for all VMs in a subscription. The details on this feature are in our documentation for Linux and Windows VMs.
The system request key, also known as the magic SysRq key, allows you to enter key combinations that will be understood by the Linux kernel regardless of its state. Like a SysRq, a non-maskable interrupt (NMI) can forcibly crash your VM, which is useful if your VM is completely frozen. In other words, we’re giving you an additional tool in your toolkit for even more of those nasty debugging situations. More details are available in our documentation for Linux and Windows VMs.
We have also focused on making the serial console more accessible for anyone with visual, hearing or physical impairments. Without the need to use a mouse, you can now tab through serial console to show exactly where you are on screen. Serial console also includes native screen reader support, meaning that your screen reader will be able to tell you exactly what is going on within your serial console.