Ubuntu freeze at swap

New Ubunt 14.04 Freeze at Swap.

Ubuntu-Swap

It is doing this because Ubuntu is trying to switch to a high resolution video mode for the console and your hardware isn’t cooperating.

Fixing this while at the machine
When Grub2 shows up:
  • Highlight the menu item for Ubuntu and press ‘e’
  • Go to the line where it loads the kernel and press ‘End’ to go to the end of the line
  • Add ‘nomodeset’
  • Press F10 or Ctrl-X to boot it
With any luck it will boot into the login screen. This won’t save that option but at least now you can edit the file for Grub2 and update it to save that option if it works.
Permernently fixed this issue
  • Log in (ssh will probably do, if you know the machine’s IP)
  • Update the grub config file nano /etc/init/grub
  • Find the line that starts with GRUB_CMDLINE_LINUX_DEFAULT
  • Edit the line to include nomodeset, in my case, the line looked like this afterwards: GRUB_CMDLINE_LINUX_DEFAULT="nomodeset"
  • Save/exit nano
  • Run update-grub
  • Reboot

Note: The easy way of doing this with modern versions of GRUB is by editing /etc/default/grub and add “nomodeset” (separated by a space) to the end of the GRUB_CMDLINE_LINUX_DEFAULT variable

 

Ubuntu Recovery Mode – Readonly File System

In Order to emergency, change configuration or reset root password. Follow following steps

1. Shutdown the computer
 2. Boot into Recovery Mode --After BIOS load, hold down Shift key to access the grub menu --Once in grub menu, select the entry ending in "(recovery mode)"
 3. From the next menu selected option to enter Root Session
 4. At the root session, execute command mount -o remount,rw / to remount the filesystem as read-write

Then after you can reset the Root password to change the configuration.

Install monit to Monitor Services (Ubuntu)

  1. Install monit
     apt-get install monit
  2. Configuring of monit
     vi /etc/monit/monitrc

    enable following line , to view the services via http

    set httpd port 2812 and
         use address localhost  # only accept connection from localhost
         allow localhost        # allow localhost to connect to the server and
         allow admin:monit      # require user 'admin' with password 'monit'
         allow @monit           # allow users of group 'monit' to connect (rw)
         allow @users readonly  # allow users of group 'users' to connect readonly
  3. Star the services
    /etc/init.d/monit start
  4. View the monit Web Interface
     http://localhost:2812
  5. Add process for monit to monitor
    – add xxx.conf file at /etc/monit/conf.d
    Example for Apache, content of apache.conf added to /etc/monit/conf.d  folder :

     check process apache with pidfile /var/run/apache2/apache2.pid
    
     start program = "/usr/bin/service apache2 start" with timeout 60 seconds
    
     stop program  = "/usr/bin/service apache2 stop"

    Example of MySQL , content of mysql.conf added to /etc/monit/conf.d folder

    check process mysqld with pidfile /var/run/mysqld/mysqld.pid
    
    group mysql
    
    start program = "/usr/bin/service mysql start"
    
    stop program = "/usr/bin/service mysql stop"
    
    if failed host 127.0.0.1 port 3306 then restart
    
    if 5 restarts within 5 cycles then timeout
  6. Restart monit , see the log at:
    /var/log/monit.log

Addting New Disk to XenServer

Here is adding new disk to XenServer

1. Login to Console
2. fdisk -l to identify which one is the disk, for example /dev/sdb
3. enter following command –

xe sr-create name-label=<Name of Storage> shared=false device-config:device=<Path of the Storage device> type=lvm

Or :
xe sr-create name-label=sdb-disk shared=false device-config:device=/dev/sdb type=lvm