Linux ate more RAM !!!!!!!!!

Linux servers are utilizing unused memory for disk caching. This makes it looks like you are low on memory, but you are not! Everything is fine!

Why ?

Disk caching makes the system much faster! There are no downsides, except for confusing newbies. It does not take memory away from applications in any way, ever!

What if I  need to run more appilication?


If your applications want more memory, they just take back a chunk that the disk cache borrowed. Disk cache can always be given back to applications immediately! You are not low on ram!

Swap ! needed ?
==============


No, disk caching only borrows the ram that applications don't currently want. It will not use swap. If applications want more memory, they just take it back from the disk cache. They will not start swapping.


How to stop ?

You can't disable disk caching. The only reason anyone ever wants to disable disk caching is because they think it takes memory away from their applications, which it doesn't! Disk cache makes applications load faster and run smoother, but it NEVER EVER takes memory away from them! Therefore, there's absolutely no reason to disable it!
Why does top and free say all my ram is used if it isn't?
This is just a misunderstanding of terms. Both you and Linux agree that memory taken by applications is "used", while memory that isn't used for anything is "free".


But what do you call memory that is both used for something and available for applications?

You would call that "free", but Linux calls it "used".
Memory that is    You'd call it    Linux calls it
taken by applications     Used     Used
available for applications, and used for something     Free     Used
not used for anything     Free     Free

This "something" is what top and free calls "buffers" and "cached". Since your and Linux's terminology differs, you think you are low on ram when you're not.
How do I see how much free ram I really have?
To see how much ram is free to use for your applications, run free -m and look at the row that says "-/+ buffers/cache" in the column that says "free". That is your answer in megabytes:

$ free -m
             total       used       free     shared    buffers     cached
Mem:          1504       1491         13          0         91        764
-/+ buffers/cache:        635        869
Swap:         2047          6       2041
$

If you don't know how to read the numbers, you'll think the ram is 99% full when it's really just 42%.

KVM Node setup Basic steps only

To use LVM-based guests, you need a volume group that has some free space that is not allocated to any logical volume.

In this example, I use the volume group /dev/vg_server1 with a size of approx. 465GB...

vgdisplay

[root@server1 ~]# vgdisplay
  --- Volume group ---
  VG Name               vg_server1
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               465.28 GiB
  PE Size               4.00 MiB
  Total PE              119112
  Alloc PE / Size       26500 / 103.52 GiB
  Free  PE / Size       92612 / 361.77 GiB
 
 
  that contains the logical volumes /dev/vg_server1/LogVol00 with a size of approx. 100GB and /dev/vg_server1/LogVol01 (about 6GB) - the rest is not allocated and can be used for KVM guests:

lvdisplay

[root@server1 ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/vg_server1/LogVol01
  LV Name                LogVol01
  VG Name                vg_server1
  LV UUID                uUpXY3-yGfZ-X6bc-3D1u-gB4E-CfKE-vDcNfw
  LV Write Access        read/write
  LV Creation host, time server1.example.com, 2012-08-21 13:45:32 +0200
  LV Status              available
  # open                 1
  LV Size                5.86 GiB
  Current LE             1500
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0

  --- Logical volume ---
  LV Path                /dev/vg_server1/LogVol00
  LV Name                LogVol00
  VG Name                vg_server1
  LV UUID                FN1404-Aczo-9dfA-CnNI-IKn0-L2hW-Aix0rV
  LV Write Access        read/write
  LV Creation host, time server1.example.com, 2012-08-21 13:45:33 +0200
  LV Status              available
  # open                 1
  LV Size                97.66 GiB
  Current LE             25000
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:1
 
 
 
  Or you can reinstall the OS and create a lvm partition as below
  =======
 
  df
====
/dev/md125              ext4      476M  150M  298M  34% /boot
/dev/mapper/lvroot-home ext4       85G  5.8G   75G   8% /home
/dev/md126              ext4       40G  3.3G   35G   9% /



Install required KVM RPMs/packages


# yum groupinstall "Virtualisation Tools" "Virtualization Platform"
# yum install python-virtinst


# chkconfig libvirtd on


# service libvirtd status
libvirtd (pid  31128) is running...
# virsh list

Setup will be like below




                    +-------------+
                     | CentOS/RHEL |             |-----|
     -->ISP router---+ Box Host w/ +--- eth0 -->-+ br0 +  Private IP
                     | KVM         |             |     |
                     +-------------+--- eth1 -->-+ br1 | Public IP
                                                 |-----|
                                                    |
                                                vm1-+---vm2----vm3---vm4
*** NOTE: each VMs will have two interface i.e. Private and Public *****

===================

Install and configure a network bridge
=============================================

 
KVM network setup
============
[root@vz2 template]# cat /etc/sysconfig/network-scripts/ifcfg-br0
DEVICE=br0
TYPE=Bridge
BOOTPROTO=static
BROADCAST=IP
IPADDR= Main IP
GATEWAY=IP
NETMASK=255.255.255.X
NETWORK=IP
ONBOOT=yes

=========

>> /etc/sysconfig/network-scripts/ifcfg-eno1


DEVICE=eno1
TYPE=Ethernet
HWADDR=check with hw
IPV6INIT=yes
IPV6_AUTOCONF=yes
ONBOOT=yes
BRIDGE=br0
==========================================================================

Next steps >> solusvm master /slave installation steps


Sreejith Anchal >> ping me @ s9400578382@gmail.com , if need.

Installation of ZendOptimizer

If you wanted to install Zend Optimizer use the below command.


Inorder to check the module is available :
/scripts/phpextensionmgr list
Available Extensions:
EAccelerator
IonCubeLoader
Zendopt
SourceGuardian
PHPSuHosin

Installing the module :
/scripts/phpextensionmgr install Zendopt
Installing Zendopt
Determining PHP version
Installing Zend Optimizer binary
Activating Zend Optimizer in /usr/local/lib/php.ini
Zend Optimizer activated
Skipping install to /usr/local/php4, missing php.ini

Installation of Cpremote

cPremote is a remote incremental backup and it will use cPanel modules itself for taking backups to your remote backup server over ssh.

A growing number of clients are choosing to use CP Remote backup script as a ‘low load’ alternative to the standard Cpanel FTP backups. CP Remote is much more cost effective than the other backup solution we offer (R1 Soft) although it is a ‘time stamped’ solution and not a continuous data protection solution.

If you are happy to have off server backups taken nightly at a pre-defined time (usually 1am) then this backup solution could be for you. Quickly have your data restored to any cpanel server in the event of data loss.

It uses Rsync which means it is a very efficient way of working. Your first backup will take the longest as it copies all files from your server to the backup space you buy from us. The second backup only backs up what has changed so it is a very efficient solution in terms of bandwidth. All your data is backed up with this solution including Public_html folder, My SQL databases as well as email folders.

The Cpanel plug in works perfectly and allows you to check your backups and also restore quickly and easily from within an easy to use web based interface.

» Requirements:
You need a Linux cPanel server running latest stable release of cPanel(11.32 or higher) .

Need cpphp /var/cpanel/3rdparty/bin/php

» Install cPremote
Download the tar file cpremote.X.Y.tar.gz from https://portal.syslint.com/downloads.php where X.Y is the latest version.
tar -xzf cpremote.X.Y.tar.gz
# cd cpremote/
# ./install.sh

» Configure Backup
Go to WHM->Plugins -> cPanel Remote Backup -> Configure Backup . Here you can configure backup settings.

» Configure Backup Public Key in remote ssh account
Go to WHM->Plugins -> cPanel Remote Backup -> Your Backup Public Key and follow the procedure mentioned in that website to setup public key for backup ssh account.

» How to run a manual backup update
You may need to run the following script.
/scripts/cpremotebackup

» How to change the backup time
You may change the following cron time
0 1 * * * /scripts/cpremotebackup

» How to enable backup for Multiple Home folder
You may need to add your home folders mount point names n to the file /etc/cpremote/userhomes.txt. See an example below, It is the default settings.
/home
/home1
/home2
/home3
This option will enable multiple home folder feature.

» How to restore a cPremote Backup
1. A full account from daily , weekly, monthly and 7 days backups
2. Restore email fodler , home fodler , document root , individual files and fodlers, individual databases
3. cPanel end user interface for restoring backups
4. /scripts/cpremoterestore feature rich command line utility

» Restore Backups from Plugin Page
You may need to goo WHM -> Plugins -> cPanel Remote Backups -> Restore A backup , then select the cpanel accounts and backup option for restore.

» Restore Backups from server shell
If you need to restore a cPanel account say CPUSER from the backups see , the example commands below,

Restore email folder of cpanel user CPUSER from the daily backups
/scripts/cpremoterestore --user=CPUSER --from=daily --type=mail

Restore Document root from weekly backup for CPUSER
/scripts/cpremoterestore --user=CPUSER --from=weekly --type=www

Restore the complete home folder of CPUSER from monthly backup
/scripts/cpremoterestore --user=CPUSER --from=monthly --type=homefolder

Restore a full account from daily backup
/scripts/cpremoterestore --user=CPUSER --from=daily --type=full

Installing Ngnix on Cpanel

 Nginx can be used to serve static pages on a server running cPanel with Apache. Apache will handle the dynamic content for PHP and cgi scripts, while nginx will handle the static pages such as .htm and .html

Install nginx
 1. Make a copy of your httpd.conf file
     cp /etc/httpd/conf/httpd.conf /etc/httpd/conf/httpd.conf.bak

 2. Go to WHM > Tweak Settings and change the Apache port:
    The port on which Apache listens for HTTP connections. Specifying a specific IP will prevent   Apache from listening on all other IPs. (default: 0.0.0.0:80)  To:  0.0.0.0:8081
     Do not change the https port listed.
     Click the “Save” button.

3. Grab a copy of the nginx installation script:
     mkdir /root/cpacct && cd /root/cpacct
     cd /usr/local/src
     wget http://nginxcp.com/latest/nginxadmin.tar
     tar xf nginxadmin.tar
     cd publicnginx
    ./nginxinstaller install

 If you receive this error when trying to install:
  access key doesn't exist create it in WHM
  Then go to WHM > Cluster/Remote Access > Setup Remote Access Key and click on the “Generate      New Key” button.
  At that point, then re-run “./nginxinstaller install” command.

4. Rebuild Apache and then restart nginx and Apache
    /scripts/rebuildhttpdconf
    /etc/init.d/nginx restart
    /etc/init.d/httpd restart

Now, your static pages should be serving from nginx, while PHP and cgi ones should be serving from Apache. Both httpd and nginx processes will be running on the machine.

Please note that sites will still show up on port 80 in a browser (so you don’t have to worry that pages in a browser will require a different port). nginx works as a proxy on port 80, so it handles the incoming requests on that port to see if they are dynamic or static, then it hands off the dynamic pages to Apache (running on port 8081). Your site visitors will have no idea that Apache is running on a different port due to the proxying nginx performs on the machine for it.

Uninstall nginx

If you decide you want to uninstall nginx at any point, simply run this command:
/root/cpacct/publicnginx/nginxinstaller uninstall
You would also need to go to WHM > Tweak Settings and change the Apache port back to 80:
The port on which Apache listens for HTTP connections. Specifying a specific IP will prevent Apache from listening on all other IPs. (default: 0.0.0.0:80)  To: 0.0.0.0:80
Then “Save” that area. Finally, rebuild and restart Apache:
  /scripts/rebuildhttpdconf
  /etc/init.d/httpd restart

Changing Litespeed webserver password

Login to the server
/usr/local/lsws/admin/misc/admpass.sh

Enter the user name:
New Password:
Retype New Password:

The password have been changed
============================================

Wordpress Installation in Cpanel

Step 1: Download the installation archive from the WordPress download section (http://wordpress.org/download/) by clicking on "Download.zip" or "Download.tar.gz". This way you will get the latest stable release of the WordPress application.

Step 2: When you are in cPanel -> File Manager, navigate to the uploaded file and extract it by clicking on "Extract". The other option is to extract the file on your computer and then to upload the content in the desired folder via FTP.

Step 3: You have to create a Mysql database and a database user and then assign that user in to the database with full privellages.

Step 4: Then you have to run the installer,With the new version of WordPress, you don’t have to edit your config. file anymore. Simply type the url of the directory where it was installed.

    For example: www.yourdomain.com/blog/





In cpanel case, you will need to add user_database format when you enter the name of your database. Enter the database you created in the step 2. Enter the username and password and thats it. You don’t need to change Database host and wp_prefix field.
Once you hit the submit button, it will take you to a follow up page like this :



Make sure that you check the box off if you don’t want this blog to be seen by search engines. For businesses, keep it on so you can be discovered. Make sure you enter a valid email because if something goes wrong, and your browser decide to shut off on you, and you didn’t get to copy the random password, it can send the password to you. Once you click install, a confirmation screen like below would appear:


After the step above, your installation is now complete and you can login to your WordPress admin panel by going to:

    http://www.yourdomain.com/wp-admin

Eventhough the install is complete, there is more that awaits you such as choosing the right theme, plugins, and advertising your blog.