If you plan to run high traffic wordpress blog(wordpress nginx), i would suggest to run it in virtual private server (VPS) or dedicated server together with NGINX FastCGI Caching.
Besides the low memory consumption when using Nginx as a web server, it has a fast performance. When you combine Nginx and FastCGI Caching module, you will further enhance the performance of your web application, including a WordPress site.
A web server generally hosts the web content, and responds to requests for this content from web browsers such as Internet explorer, Google chrome and Firefox. The example of web server are apache web server, IIS web server, Nginx webserver and litespeed web server. Continue reading “How to Install and Setup Apache Web Server in Linux”
389 Directory Server (previously Fedora Directory Server) is an open source enterprise class LDAP server for Linux. It is developed by Red Hat community-supported Fedora Project. The name 389 is derived from the port number for LDAP.
In this article we will guide you through the steps on how to install and setup 389 directory server on CentOS 7.
Steps to Install and Setup 389 Directory Server on CentOS 7
1. Turn off selinux :
vi /etc/sysconfig/selinux
Change SELINUX to disabled then reboot the server :
# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing - SELinux security policy is enforced.
# permissive - SELinux prints warnings instead of enforcing.
# disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of three two values:
# targeted - Targeted processes are protected,
# minimum - Modification of targeted policy. Only selected processes are protected.
# mls - Multi Level Security protection.
SELINUXTYPE=targeted
2. Perform basic performance and Security tuning for LDAP server :
# setup-ds-admin.pl
==============================================================================
This program will set up the 389 Directory and Administration Servers.
It is recommended that you have "root" privilege to set up the software.
Tips for using this program:
- Press "Enter" to choose the default and go to the next screen
- Type "Control-B" then "Enter" to go back to the previous screen
- Type "Control-C" to cancel the setup program
Would you like to continue with set up? [yes]:
==============================================================================
Your system has been scanned for potential problems, missing patches,
etc. The following output is a report of the items found that need to
be addressed before running this software in a production
environment.
389 Directory Server system tuning analysis version 23-FEBRUARY-2012.
NOTICE : System is x86_64-unknown-linux3.10.0-327.4.5.el7.x86_64 (2 processors).
Would you like to continue? [yes]:
==============================================================================
Choose a setup type:
1. Express
Allows you to quickly set up the servers using the most
common options and pre-defined defaults. Useful for quick
evaluation of the products.
2. Typical
Allows you to specify common defaults and options.
3. Custom
Allows you to specify more advanced options. This is
recommended for experienced server administrators only.
To accept the default shown in brackets, press the Enter key.
Choose a setup type [2]:
==============================================================================
Enter the fully qualified domain name of the computer
on which you're setting up server software. Using the form
.
Example: eros.example.com.
To accept the default shown in brackets, press the Enter key.
Warning: This step may take a few minutes if your DNS servers
can not be reached or if DNS is not configured correctly. If
you would rather not wait, hit Ctrl-C and run this program again
with the following command line option to specify the hostname:
General.FullMachineName=your.hostname.domain.name
Computer name [centos72.ehowstuff.local]:
==============================================================================
The servers must run as a specific user in a specific group.
It is strongly recommended that this user should have no privileges
on the computer (i.e. a non-root user). The setup procedure
will give this user/group some permissions in specific paths/files
to perform server-specific operations.
If you have not yet created a user and group for the servers,
create this user and group using your native operating
system utilities.
System User [nobody]: ldap
System Group [nobody]: ldap
==============================================================================
Server information is stored in the configuration directory server.
This information is used by the console and administration server to
configure and manage your servers. If you have already set up a
configuration directory server, you should register any servers you
set up or create with the configuration server. To do so, the
following information about the configuration server is required: the
fully qualified host name of the form
.(e.g. hostname.example.com), the port number
(default 389), the suffix, the DN and password of a user having
permission to write the configuration information, usually the
configuration directory administrator, and if you are using security
(TLS/SSL). If you are using TLS/SSL, specify the TLS/SSL (LDAPS) port
number (default 636) instead of the regular LDAP port number, and
provide the CA certificate (in PEM/ASCII format).
If you do not yet have a configuration directory server, enter 'No' to
be prompted to set up one.
Do you want to register this software with an existing
configuration directory server? [no]:
==============================================================================
Please enter the administrator ID for the configuration directory
server. This is the ID typically used to log in to the console. You
will also be prompted for the password.
Configuration directory server
administrator ID [admin]:
Password:
Password (confirm):
==============================================================================
The information stored in the configuration directory server can be
separated into different Administration Domains. If you are managing
multiple software releases at the same time, or managing information
about multiple domains, you may use the Administration Domain to keep
them separate.
If you are not using administrative domains, press Enter to select the
default. Otherwise, enter some descriptive, unique name for the
administration domain, such as the name of the organization
responsible for managing the domain.
Administration Domain [ehowstuff.local]:
==============================================================================
The standard directory server network port number is 389. However, if
you are not logged as the superuser, or port 389 is in use, the
default value will be a random unused port number greater than 1024.
If you want to use port 389, make sure that you are logged in as the
superuser, that port 389 is not in use.
Directory server network port [389]:
==============================================================================
Each instance of a directory server requires a unique identifier.
This identifier is used to name the various
instance specific files and directories in the file system,
as well as for other uses as a server instance identifier.
Directory server identifier [centos72]:
==============================================================================
The suffix is the root of your directory tree. The suffix must be a valid DN.
It is recommended that you use the dc=domaincomponent suffix convention.
For example, if your domain is example.com,
you should use dc=example,dc=com for your suffix.
Setup will create this initial suffix for you,
but you may have more than one suffix.
Use the directory server utilities to create additional suffixes.
Suffix [dc=ehowstuff, dc=local]:
==============================================================================
Certain directory server operations require an administrative user.
This user is referred to as the Directory Manager and typically has a
bind Distinguished Name (DN) of cn=Directory Manager.
You will also be prompted for the password for this user. The password must
be at least 8 characters long, and contain no spaces.
Press Control-B or type the word "back", then Enter to back up and start over.
Directory Manager DN [cn=Directory Manager]:
Password:
Password (confirm):
==============================================================================
The Administration Server is separate from any of your web or application
servers since it listens to a different port and access to it is
restricted.
Pick a port number between 1024 and 65535 to run your Administration
Server on. You should NOT use a port number which you plan to
run a web or application server on, rather, select a number which you
will remember and which will not be used for anything else.
Administration port [9830]:
==============================================================================
The interactive phase is complete. The script will now set up your
servers. Enter No or go Back if you want to change something.
Are you ready to set up your servers? [yes]:
Creating directory server . . .
Your new DS instance 'centos72' was successfully created.
Creating the configuration directory server . . .
Beginning Admin Server creation . . .
Creating Admin Server files and directories . . .
7. Start the dirsrv admin service and dirsrv instance :
This article will describe on how to move or migrate LVM and volume group from one server to another.
If you are working in a production environment then you have to know about the software disk management and all the methods to provide flexibility in storage management.
LVM stand for logical volume management. It is a tool to manage and provides a higher-level view of the disk storage.
Below tutorial will be very useful for system administrators who have problems on the linux operating system and want to mount the mounted partition to other systems.
This should be the most simple recovery strategy if we run Linux in VMware virtual machines.
Migrating LVM or Volume Group to new server should be the fastest way to access the important linux partition that may contains user’s data or important configuration files.
How to Migrate LVM or Volume Group to New Server
1. Add vdisk to new virtual machine.
a) Click “Add” to proceed :
b) Select “Hard Disk” device type :
c) Please choose “Use and existing virtual disk” :
d) Browse to vdisk location :
e) Click Next to proceed :
f) Click finish :
g) Finally click “OK” to complete :
2. Once the vdisk as been added to new Linux server, please proceed to rescan the linux VM.
3. Check the new disk. The second vdisk by default will be recognised as /dev/sdb. Since the partition type has been formatted as LVM on the previous system, it will show Id “8e” if you run fdisk command.
# fdisk -l
..
..
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xce931872
Device Boot Start End Blocks Id System
/dev/sdb1 1 1305 10482381 8e Linux LVM
There are two method to register and activate the LVM and volume group into new linux server. Proceed to steps 4 – 9 for Method 1. Go to step 10 for Method 2.
4. Use lvscan to scans all known volume groups or all supported LVM block devices in the system for defined Logical Volumes. The output consists of one line for each Logical Volume indicating whether it is active or inactive :
# lvscan
inactive '/dev/vg_newlvm/newvol' [9.99 GiB] inherit
ACTIVE '/dev/vg_centos66/lv_root' [30.00 GiB] inherit
ACTIVE '/dev/vg_centos66/lv_swap' [8.00 GiB] inherit
5. Check existing volume group and logical volume:
# vgscan
Reading all physical volumes. This may take a while...
Found volume group "vg_newlvm" using metadata type lvm2
Found volume group "vg_centos66" using metadata type lvm2
One of the logical volume in “vg_newlvm” volume group still inactive status.
# lvscan
inactive '/dev/vg_newlvm/newvol' [9.99 GiB] inherit
ACTIVE '/dev/vg_centos66/lv_root' [17.51 GiB] inherit
ACTIVE '/dev/vg_centos66/lv_swap' [2.00 GiB] inherit
6. Export the volume group “vg_newlvm” :
# vgexport vg_newlvm
Volume group "vg_newlvm" successfully exported
7. Then import volume group “vg_newlvm”:
# vgimport vg_newlvm
Volume group "vg_newlvm" successfully imported
8. To activate volume groups “vg_newlvm”, run the following command :
# vgchange -ay vg_newlvm
1 logical volume(s) in volume group "vg_newlvm" now active
9. Check again updated logical volume and volume group status :
# lvscan
ACTIVE '/dev/vg_newlvm/newvol' [9.99 GiB] inherit
ACTIVE '/dev/vg_centos66/lv_root' [17.51 GiB] inherit
ACTIVE '/dev/vg_centos66/lv_swap' [2.00 GiB] inherit
Method 2 :
10. The fastest method to activate the migrated LVM or Volume Group are as below :
# lvscan
inactive '/dev/vg_newlvm/newvol' [9.99 GiB] inherit
ACTIVE '/dev/vg_centos66/lv_root' [17.51 GiB] inherit
ACTIVE '/dev/vg_centos66/lv_swap' [2.00 GiB] inherit
Use lvchange command to activate the LVM.
# lvchange -ay /dev/vg_newlvm/newvol
# lvscan
ACTIVE '/dev/vg_newlvm/newvol' [9.99 GiB] inherit
ACTIVE '/dev/vg_centos66/lv_root' [17.51 GiB] inherit
ACTIVE '/dev/vg_centos66/lv_swap' [2.00 GiB] inherit
In CentOS 7 and RHEL 7, the systemd process replaces the init process for starting services at boot time and also for changing the runlevels. It uses “targets” instead of run-levels and relies on systemctl command to change runlevel or to change the target.
The systemd provides much more control than the init process does while still supporting existing init scripts.
Take note that in RHEL 7 and CentOS 7, any edits of /etc/inittab file will not take effect.
The following articles describe how to change default runlevel in CentOS 7 / RHEL 7.
1. How to determine the state that the system currently configured to boot to :
# systemctl get-default
Example 1 : If the system running on Non-GUI Mode, “systemctl get-default” command will return “multi-user.target” :
[root@centos72-gui ~]# ls -al /etc/systemd/system/default.target
lrwxrwxrwx. 1 root root 36 Jun 5 2015 /etc/systemd/system/default.target -> /lib/systemd/system/graphical.target
However, you can still use the runlevel command as it was left intact for backward compatibility:
[root@centos72 ~]# runlevel
N 3
[root@centos72-gui ~]# runlevel
N 5
In case you are required to change from your CentOS 7 from Non-GUI (text-based) mode to GNOME Desktop mode, you have to ensure the following group of packages has been installed properly :
a) Server with GUI (This is for server) b) GNOME Desktop c) Graphical Administration Tools
3. How to list all currently loaded and available targets :
# systemctl list-units -t target
UNIT LOAD ACTIVE SUB DESCRIPTION
basic.target loaded active active Basic System
cryptsetup.target loaded active active Encrypted Volumes
getty.target loaded active active Login Prompts
graphical.target loaded active active Graphical Interface
local-fs-pre.target loaded active active Local File Systems (Pre)
local-fs.target loaded active active Local File Systems
multi-user.target loaded active active Multi-User System
network.target loaded active active Network
paths.target loaded active active Paths
remote-fs-pre.target loaded active active Remote File Systems (Pre)
remote-fs.target loaded active active Remote File Systems
slices.target loaded active active Slices
sockets.target loaded active active Sockets
swap.target loaded active active Swap
sysinit.target loaded active active System Initialization
timers.target loaded active active Timers
In below example, the following target are required to be laoded :
graphical.target loaded active active Graphical Interface
multi-user.target loaded active active Multi-User System
How to Change default runlevel
4. How to Change default runlevel from Non-GUI (text-based) mode to GNOME Desktop in CentOS 7 / RHEL 7
# systemctl set-default multi-user.target
5. How to Change default runlevel from GNOME Desktop to Non-GUI (text-based) mode in CentOS 7 / RHEL 7