Dewlance® Forum - Linux Xen-HVM, KVM VPS - Tutorials

[Solved] KVM virsh command hang

Mon, 05 Sep 2016 07:15:40 -0400

Sometimes KVM virsh command hang but it can be solved by just restarting a libvirtd.

Run this command:
service libvirtd restart

Note: If RAID array is rebuilding or server load is high then it can take few minute.

Now you can run your virsh command but first time it will take few minute so you need to wait for few minute and once it start working then it will not hang.

You can buy SSD KVM VPS from http://dewlance.com/cheap-xenpv-vps (KVM VPS, not xen)

How to find a cheap Windows VPS and which solution is the best and the affordable

Tue, 20 Aug 2013 08:12:17 -0400

Windows is an operating system like Linux and people use it because it is loaded with tons of features, a user friendly GUI and it is even possible to run it on 256MB of RAM, although it is recommended to use at least 512MB to 1GB of RAM.

Finding a great and well-established Cheap Windows VPS company is not so hard but takes a lot of time. Many hosting companies are not even registered, which poses a high risk that the company itself may close doors at any time.

1.Only look for registered hosting companies:
You can take legal action against these but if the company you are dealing with is unregistered, you will find it difficult to acquire their office address, let alone sue them.

2. VPS Uptime
Your business is important and you can be frustrated with Windows VPS, which is frequently down or unstable, so it will be good to introduce yourself to their SLA agreement.

3. Robust customer support
For the usual customers, a 6 to 12 hours response time is normal, however, for hosting companies, even 5 minutes are problematic, so better check it before purchasing the service.

4. Guaranteed Bandwidth
Sellers of hosting services over-commit bandwidth and sell you bandwidth of up to 10TB at a price of between $10 to $20 per month, which is not possible without overselling.

5. The control panel of your Windows VPS
You should look for a VPS with control panel, which allows you to reboot, shutdown and re-install an OS in emergency.

There are more ways to check it like using the phone support or just look for a well-established company. New technology upgrades are being introduced on almost a daily basis so it is advisable to determine what technology they are using and how they are capable of delivering it to you. Examine how they handle complains and inform yourself on the history of the company.

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How to Upgrade XEN to 4.1.4 on CentOS?

Thu, 25 Apr 2013 15:30:15 -0400

Hello,

First you need to check your Xen Version by typing a command in your SSH Client

Quote:xm info
xl info

You will get a 10 to 20 line output result but you need to check only this 3 lines..
xen_major : 4
xen_minor : 1
xen_extra : .1

It means your Xen version is 4.1.1

If both commands are not working then you can check your Xen version from /etc/grub.conf file..

Command:

Quote:nano /etc/grub.conf

output result

Quote:default=0 << If set to 3 then check 3rd title
timeout=10
splashimage=
hiddenmenu
title CentOS (3.2.12-434.3.2.el5xen)
root (hd0,0)
kernel /xen.gz-4.2.1 <<< YOUR XEN VERSION
module /vmlinuz-4.2.1.el5xen ro
module /initrd-4.2.1.el5xen.img << << Your Xen Version
title CentOS (xyz)

How to Upgrade Xen? (If you don't want to change your whole version from 3.x to 4.x.
Upgrade Kernel:

Quote:yum upgrade kernel-xen*

How to Upgrade Xen Version from 3.x to 4.1.4? (Warning: Do this at your own risk)

Run this command

Quote:cd /etc/yum.repos.d

Now download latest version of Xen repo from Gitco: (If you want to install your selected repo then go to and replace with your repo url in wget command

Command:

Quote:wget removed

Now we need to remove Xen:

Quote:yum remove xen

Quote:yum remove kernel-xen*

Once you remove Xen and Xen kernel then you can install latest Xen by running this command:

Quote:yum install xen

Edit /boot/grub/grub.conf and change "default 0" to your new xen kernel line..(Eg: If your newly installed kernel title listed on 1st line then change to "default 0", If listed on 2nd then change to "default 1")

For example: (Only for example, don't replace your grub config with this config otherwise your server will stop working)

Quote:nano /etc/grub.conf

PHP Code:
default=1
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (OpenVZ)
        root 
        kernel /vmlinuz-example
        initrd /initrd-example.el5.img
title CentOS (Xen)
        root (hd0,0)
        kernel /xen.gz-4.1.4
        module /vmlinuz-4.1.4.el5xen ro root=LABE
        module /initrd-4.1.4.el5xen.img 

Now reboot your vps/server

Quote:reboot

After rebooting VPS/Server you can verify your Xen Version by running a xm info command or xl info.

How to Install Xen Virtualization on CentOS?

Fri, 13 May 2011 03:36:11 -0400

Hello,

Note: This tutorial is only for CentOS 5.+ and maybe work on other versions.

Xen Installation Commands:

1. Install Virtualization

Quote:yum groupinstall Virtualization

2. Edit grub.conf to reflect the correct default Kernel

Quote:nano /etc/grub.conf

# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00
# initrd /initrd-version.img
#boot=/dev/sda

PHP Code:
default=0
timeout=1
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (2.6.18-92.1.10.el5xen)
        root (hd0,0)
        kernel /xen.gz-3.3.0
        module /vmlinuz-2.6.18-92.1.10.el5xen ro root=/dev/VolGroup00/LogVol00
        module /initrd-2.6.18-92.1.10.el5xen.img
title CentOS (2.6.18-92.1.10.el5)
        root (hd0,0)
        kernel /vmlinuz-2.6.18-92.1.10.el5 ro root=/dev/VolGroup00/LogVol00
        initrd /initrd-2.6.18-92.1.10.el5.img
title CentOS (2.6.18-92.el5)
        root (hd0,0)
        kernel /vmlinuz-2.6.18-92.el5 ro root=/dev/VolGroup00/LogVol00
        initrd /initrd-2.6.18-92.el5.img 

Reboot the machine for new XEN kernel to take effect

Quote:reboot

After the reboot check the Kernel to reflect the change

Quote:uname -r

Result: 2.6.18-53.1.21.el5xen

Enjoy

How to Install Firefox by SSH Command? - CentOS or Ubuntu

Wed, 27 Apr 2011 14:27:51 -0400

Tutorial: How to install firefox by SSH command.

Sometimes I can't install firefox through "Add/Remove Software" so lots of time I install Firefox though SSH on CentOS or Ubuntu.

Install Firefox on CentOS by SSH:

Quote:yum install firefox

If ask for a permission to install then press y

On Ubuntu

Quote:sudo apt-get update

Quote:sudo apt-get install firefox-3.0

If last command not work then try this command

Quote:sudo apt-get install firefox

Also you can use this command

Quote:apt-get install firefox

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How to secure SSH/SSHD?

Fri, 25 Feb 2011 09:48:50 -0500

Hi,

I heard that the most common way for a linux machine to be hacked is through SSH/SSHD. How can I secure my SSH using keys?

How to change root password from ssh command?

Thu, 24 Feb 2011 08:14:43 -0500

If you've a root permission then you can change anyone's account password.

How to change root password from ssh command?

Quote:passwd root

You can change any account's password,

You can change any user's password, for example If I have a account "admins" then I can change "admins" account password with this command:

passwd admins

How to login in SSH? and TOP useful SSH Commands

Sat, 31 Jul 2010 23:12:04 -0400

Hello,

First you need to Install SSH Client Software on your PC.

You can use Open Source Putty

Download Putty(Open Source)

Open Putty and then enter your main IP address in "Host Name(or IP Address)"

  putty-config.jpg (Size: 33.85 KB / Downloads: 0)
click on "ok"

Now Enter your user name and password (Your Default user name is: root)

  putty-login.jpg (Size: 6.83 KB / Downloads: 0)

If you login successfully then show this type of message in putty "~root@examle"

  putty-logged-in.jpg (Size: 14.08 KB / Downloads: 0)

Some SSH useful commands:

1. Directory Access

Code:
cd /YourDirectory

2. Delete File/folder

Quote:rm examplefile.ext

Delete file & folders without conformation(be careful)

Quote:rm -rf ExampleFile

Create File:

Quote:touch Filename.EXT

(.EXT = File Extension Name)

Edit File:

Quote:nano Filename.txt

Quote:pico /home/username/public_html/index.html

(edit the index page for the user's website)
or

Quote:vi /home/username/public_html/index.html

(edit the index page for the user's website)

Change File Permission

Quote:chmod 775

0 = --- No permission
1 = --X Execute only
2 = -W- Write only
3 = -WX Write and execute
4 = R-- Read only
5 = R-X Read and execute
6 = RW- Read and write
7 = RWX Read, write and execute

Change Owner and Group Permission

Quote:chown username:username Filename

- ChangeGroup Permission

Quote:chown username Filename

- Change Owner Permission
For Example: chown root:root myfile.txt

Move File
mv oldfilename newfilename

Download Files from Internet to your VPS

Quote:wget http://example.com/filename/file.tar.gz

Extract & Create TAR Files
tar -zxvf file.tar.gz: Extracts the file
tar -xvf file.tar: Extracts the file
tar -cf archive.tar contents/ : Takes everything from contents/ and puts it into archive.tar

shows who logged in and when...

Quote:last -20

(shows only the last 40 logins)

Quote:last -40 -a

(shows last 40 logins, with the hostname in the last field)

Currently Loggid in User

Quote:w

(shows who is currently logged in and where they are logged in from)

Quote:who

(This also shows who is on the server in an shell)