How to change cputune dynamic? - kvm

Can I change the cputune when VM is running?
I remember that there is a virsh command to change this parameter when VM is running.
Thanks.

virsh vcpupin command can be used for pinning vcpus to host cpus on a running guest.

Related

SSH'ing from windows 10 into wsl2 ubuntu

I am fairly new to this business and I fail to understand how to SSH from my win10 machine into my installed wsl2 ubuntu 20.4
Basically, I followed this tutorial, But I keep getting the following errors:
when I try to SSH using the public port (using curl ifconfig.me) gives me the error "connection timed out"
when I try to SSH using the private port (using ip route get 1.2.3.4 | awk '{print $7}') it gives me the error "Permission denied"
at some point I got the error "sshd: no hostkeys available -- exiting" so I followed this fix but then I got the errors mentioned before. Should I delete any from the /etc/ssh folder?
The end-goal is ssh'ing through vs-code, but I guess once I could do it from powershell, it's the same from vs-code.
It appears that you need to enter /etc/ssh/sshd_config (with sudo permissions) and change the following lines:
ChallengeResponseAuthentication yes
PasswordAuthentication yes
Since you seem to have fixed your issue with ssh, let me propose that your ultimate goal ("ssh into WSL from VSCode) might be better accomplished using Microsoft's "Remote Development" extension pack, which includes several extensions. While it sounds like you are considering using the "Remote - SSH" extension, you can also use the "Remote - WSL" extension directly.
After installing either the extension pack or the WSL extension directly, just open your WSL instance, cd to the directory with your code and then code . (including the period). This will open VSCode and install a shim into the WSL instance which will allow communication between the two.
See the docs from Microsoft for more detail.
Also, on the topic of your original question, you said that you edited sshd_config to permit password authentication (I don't think the ChallengeResponseAuthentication change was necessary). That's one way to go, but ultimately I'd recommend generating an SSH key pair, copying the private key to something like C:\Users\yourid\.ssh\id_rsa and using that instead of a password login.
And you mentioned in your original question that you were unable to access SSH on the public port. This is because WSL2 does not do NAT, so it also won't be accessible from a second computer without (a lot of) additional effort (manual port-forwarding from Windows to WSL, which will have to be reset on reboot since the WSL interface address will change).
As you've discovered, the WSL interface address will work, but remember that it will change on each reboot of Windows (technically, I think, any time the WSL subsystem is shut down and restarted). IMHO, you're better off using 127.0.0.1 or localhost.
But really, my preferred method of accessing WSL remotely is to install OpenSSH on Windows 10, port 22. Then you can simply do something like ssh -t windowsusername#mycomputername.local wsl to get access to the WSL instance. You can even do this when you have multiple WSL instances on your machine with ssh -t windowsusername#mycomputername.local wsl -d WSLInstanceName.
If you use this technique, of course, and you still want to run an SSH server in a WSL instance, you'll need to use a different port. But I really think you should do this anyways when running SSH under WSL. Otherwise, you are likely to spin up a second WSL instance at some point and run into port conflicts anyway.
The downside is that the Windows OpenSSH -> WSL hack won't allow you to run things like VSCode through SSH, but it does provide super-simple access to WSL through SSH, and works remotely (if you ever need that) as well.

Need to install Firefox browser on Hortonworks Sandbox virtual machine (HDP 2.4) running in Virtual Box 5.0.16

I am new to Hadoop and the Big Data world...
I have installed the Hortonworks Sandbox VM in Virtual Box. It's working great...
Can someone tell me how to install Firefox within the VM? I need it to use NIFI
Thanks a lot for any help!
Installing a browser on the VM and using it through VNC will typically be very slow. The best option is to set up an SSH Tunnel and do a local forward. If you use the PuTTy ssh client on windows then you can follow the following instructions on setting up the local forward which will allow you to use your browser on the host operating system to connect to the NIFI instance running in your VM.

Accessing Dev Environment from another VM (Virtualbox)

On my OSX machine I have two VM's running:
Development Environment (aka DE) (Linux)
Testing Environment (aka TE) (Win7 IE9)
In my TE, I would like to be able to access a server running on my DE. Pretty straight forward sounding but I'm sort of new.
I'm using Virtualbox as my client on both machines. My dev environment is a vagrant box setup with puppet. I can modify it with virtualbox as well for now. SIMPLEST solution wins. I have tried nested-boxing, it doesn't work :P
I was able to achieve the desired results much more easily than I had anticipated. I had to add the same lines I added to my local machine to my VM.

is there a way to find the hostname of a vm within the vm?

I am using EL5. From the host machine virsh list works to list the vms running on that machine, but how to know the vice-versa ?
Thanks.
That all depends on what OS the VM is. If the VM is linux, then, inside the VM, you can type hostname in the command line to get the hostname. In windows, start > run > "sysdm.cpl" will tell you the computer name via GUI. So there's really no way to give one-size-fits-all answer since each OS does it differently.

Remote Profiling Jprofiler

Hi i am very new to Jprofiler & Linux.
I am trying to Monitor my Apache Tomcat server installed on a linux machine from Jprofiler remote profiling which is installed on windows machine. Kindly help me in the procedure in detail.
I tried all the Help i could get from google but still stuck..any help will is appreciated. Thanks in advance.
In any case, you should extract the JProfiler tar.gz file for Linux on the remote machine. No further configuration is required on the remote side. On the local side you need a full installation of JProfiler.
There are two ways to get remote profiling to work:
A. Attach to the running Tomcat process
Execute the command line utility bin/jpenable in the JProfiler distribution on the remote machine and select the Tomcat process. The JVM will then be ready for profiling. If the profiled JVM is not listed, execute jpenable as the same user that runs the Tomcat JVM. If that does help, use alternative B.
On the local machine, create a session of type "Attach to profiled JVM (local or remote)", specify the host name of the remote machine and the profiling port that was set with jpenable.
When you start session, the JProfiler GUI will connect to the remote machine and you will see profiling data.
B. Use the integration wizard
Execute the command line uutility bin/jpintegrate in the JProfiler distribution on the remote machine and select your application server and follow the subsequent steps.
Then, proceed as in alternative A. This option is actually preferable to alternative A and unless you have to profile an already running JVM, you should take this route.