A kernel is the core of an operating system. It is the first part of the
operating system that is loaded into memory when a computer boots up (i.e.,
starts up), and it controls virtually everything on a system. The numerous
messages generated by the kernel that appear on the display screen as a
computer boots up show the hardware devices that the kernel detects and
indicate whether it is able to configure them.

dmesg obtains its data by reading the kernel ring buffer. A buffer is a
portion of a computer’s memory that is set aside as a temporary holding place
for data that is being sent to or received from an external device, such as a
hard disk drive (HDD), printer or keyboard. A ring buffer is a buffer of
fixed size for which any new data added to it overwrites the oldest data in
it.

dmesg can be very useful when troubleshooting or just trying to obtain
information about the hardware on a system. Its basic syntax is

dmesg [options]

Invoking dmesg without any of its options (which are rarely used) causes it to
write all the kernel messages to standard output. This usually produces far
too many lines to fit into the display screen all at once, and thus only the
final messages are visible. However, the output can be redirected to the less
command through the use of a pipe (designated by the vertical bar character),
thereby allowing the startup messages to be viewed one screenful at a time:

dmesg | less

less allows the output to be moved forward one screenful at a time by pressing
the SPACE bar, backward by pressing the b key and removed by pressing the q
key. (The more command could have been used here instead of the less command;
however, less is newer than more and has additional functions, including the
ability to return to previous pages of the output.)

When a user encounters a problem with the system, it can be convenient to
write the output of dmesg to a file and then send that file by e-mail to a
system administrator or other knowledgeable person for assistance. For
example, the output could be redirected to a file named boot_messages using
the output redirection operator (designated by a rightward facing angle
bracket) as follows:

dmesg > boot_messages

Because of the length of the output of dmesg, it can be convenient to pipe its
output to grep, a filter which searches for any lines that contain the string
(i.e., sequence of characters) following it. The -i option can be used to
tell grep to ignore the case (i.e., lower case or upper case) of the letters
in the string. For example, the following command lists all references to USB
(universal serial bus) devices in the kernel messages:

dmesg | grep -i usb

And the following tells dmesg to show all serial ports (which are represented
by the string tty):

dmesg | grep -i tty

The dmesg and grep combination can also be used to show how much physical
memory (i.e., RAM) is available on the system:

dmesg | grep -i memory

The following command checks to confirm that the HDD(s) is running in DMA
(direct memory access) mode:

dmesg | grep -i dma

The output of dmesg is maintained in the log file /var/log/dmesg, and it can
thus also be easily viewed by reading that file with a text editor, such as
vi or gedit, or with a command such as cat, e.g.,

cat /var/log/dmesg | less

Recurrent reboot issue could be due to faulty hard disk. If a read error or
bad block occurs, the sector will be marked as faulty. So check the hard
drive health using smartctl tool (for example: smartctl -a /dev/sda).

If you could not spot any errors, ask NOC to check the hardwares like RAM,
cooler fan, etc..

1. Log-in to the HyperVM control panel :
2. Rebuild the OS
3. Choose the centos-4-i386-afull template

Now download the LXAdmin SSE installer script (apache/bind) available from the
LXLabs download center. Login to vps shell and download this script.

wget
http://download.lxlabs.com/download/lxadmin/production/lxadmin-install-master.sh

sh lxadmin-install-master.sh

Once the shell script has completed you have LXAdmin installed. You need to
get yourself logged in as admin and change the password.

HyperVM advanced features allow you to manage your vps hosting from a single console. HyperVm has been optimized for allowing you to have HyperVM clustered servers from anywhere in the world. These are some of HyperVM features:

Quote Taken from http://lxlabs.com/software/hypervm/

* “Full Distribution.”
* “Manage your entire data center.”
* “HyperVM is successfully used by our clients to manage 1000s of vpses on 100s of servers.”
* “Support for Windows Virtualization.”
* “HyperVM allows efficient windows virtualization with advanced features like backup/restore built in.”
* “Support for multiple virtualization technologies.”
* “Live Migrate”

This install of HyperVM is for Fedora Core servers, and this install was done on Fecora Core 6. This will use the XEN  kernel, memory will be set at a dedicated limit. The limit will allow customers programs to run slower when they reach their limit unlike Openvnz their programs will normally crash. HyperVM will also require you to reboot after changes to the vps like memory or hard drive space. Openvnz will do these changes instantly.

* Downloading HyperVM

1. hypervm-install-master.sh
2. hypervm-install-slave.sh

* Getting Ready for Install

1. disable selinux (edit /etc/sysconfig/selinux <– change to [SELINUX=disabled])
2. setenforce 0
3. chkconfig libvirtd off
4. reboot

* Installing HyperVM

1. cd DIROFHyperVM/
2. sh ./hypervm-install-master.sh –virtualization-type=xen

If this errors during install just rerun the command and if HyperVM is already install just type yes

* Once server is booted

1. ssh into the server
2. ssh back into server cd /usr/local/lxlabs/hypervm/httpdocs/
3. Type in command prompt: lphp.exe ../bin/common/setdriver.php –server=localhost –class=vps –driver=xen
4. This can take a few minute’s to become enabled sometimes we have had issues and use service xend restart
5. In web browser to http://IP:8887 or http://IP:8888 of the host computers IPLogin is admin password is also admin change once inside
6. Once you have logged in as admin add the extra IP address on the servers to HyperVM IP POOL list
7. Go the VM tab
8. Click ADD XEN
9. Set the name vm name
10. Password
11. Number of IPs allowed to use
12. Hostname of the server
13. Gateway IP of the HOST network
14. IF you have multiple VMServers you can now select from which gateway the IP class is on
15. If you only have one leave localhost
16. Select OS
17. Click ADD
18. Select Disk quota
19. Number of backups allowed of the vps
20. Skip the next 3 they are for Openvz
21. Set VPS real memory allowed from Hosting server example: 128 256 512 all are in mb
22. CPU usage allowed from host computer in percent example of on core host: 10 20 25
23. With Single Core host you are allowed 100% if you have Dual or Quad core you are allowed 200%-400%
24. Traffic monthly in mb <— TRAFFICinGB x 1024
25. Number of IP address allowed to use
26. Check or uncheck if you allow backup schedule or backups allowed
27. Click add
28. Hypervm VPS will be installed

These are monitoring available for free of cost.

1. Nagios – Free, open source host, service and network monitoring program.
2. Zabbix – Open source solution for advanced monitoring, alerting and visualisation features.
3. Paessler IPCheck Server Monitor – Freeware edition is free for personal and non-commercial use with limitation of minimum monitoring interval of 15 minutes.
4. Website Monitoring – Runs as service on Windows NT based system, and sits in the system tray, alerts you with an icon notification and an email if your website is down or running slowly.
5. ManageEngine Website Monitoring – Monitor performance and availability of websites using HTTP and HTTPS requests, from end-user perspective. Free edition allows 5 monitors in the network.