Make LVM partition at installation time in Red Hat

Benefits of Logical Volume Management on a Small System

One of the difficult decisions facing a new user installing Linux for the first time is how to partition the disk drive. The need to estimate just how much space is likely to be needed for system files and user files makes the installation more complex than is necessary and some users simply opt to put all their data into one large partition in an attempt to avoid the issue.
Once the user has guessed how much space is needed for /home /usr / (or has let the installation program do it) then is quite common for one of these partitions to fill up even if there is plenty of disk space in one of the other partitions.
With logical volume management, the whole disk would be allocated to a single volume group and logical volumes created to hold the / /usr and /home file systems. If, for example the /home logical volume later filled up but there was still space available on /usr then it would be possible to shrink /usr by a few megabytes and reallocate that space to /home.
Another alternative would be to allocate minimal amounts of space for each logical volume and leave some of the disk unallocated. Then, when the partitions start to fill up, they can be expanded as necessary.    

Step-1
That should get you to this window, where the detected hard drive(s) are listed. This system has been selected to show the free space. To start creating partitions, select the free space and click Create.

Step-2
As on a default installation, two primary partitions and three logical volumes will be created. The first primary partition, which is a Standard partition, will be mounted at /boot, that is, it is the boot partition, where all boot-related programs will be located. The second primary partition will be the LVM Physical Volume, under which the three logical volumes will be created.
The default option on this window is Standard, which is what we want. Click Create.

Step-3
On the next window, shown here, there are three options that we have to modify. They are: Mount Point, File System Type, and Size (in megabytes). For the boot partition, the mount point will, of course, be /boot. While the default file system type on Fedora and virtually all Linux distributions is Ext4, there are other options. However, you do not have to bother about those other options. Aside from physical volume (lvm) and swap, which we will be using further later, you do not need to bother about the rest, at least for this tutorial.

Step-4
When the right options for the boot partition have been selected, the window should look just like the one shown here. Notice that for the size, 500 MB was allocated. That is the default size allocation for a boot partition on most Linux distributions. If you do not have a lot of disk space to spare, you can go lower than that. As low as, say, 100 MB. OK.

Step-5
With the boot partition out of the way, select the free space on the main window, and click Create. That should bring up the same window you saw earlier. Since the next partition is a primary partition for LVM, select LVM Physical Volume. Create.

Step-6

LVM Physical Volume

Choose this option to configure a partition or device as an LVM physical volume. This option is the only choice available if your storage does not already contain LVM Volume Groups. Note, however, that File system type must be set to physical volume (LVM)

The Create an LVM Physical Volume dialog.

Make LVM Volume Group

Choose this option to create LVM volume groups from the available LVM physical volumes, or to add existing logical volumes to a volume group.

The Make LVM Volume Group dialog.

To assign one or more physical volumes to a volume group, first name the volume group. Then select the physical volumes to be used in the volume group. Finally, configure logical volumes on any volume groups using the Add, Edit and Delete options.

You may not remove a physical volume from a volume group if doing so would leave insufficient space for that group's logical volumes. Take for example a volume group made up of two 5 GB LVM physical volume partitions, which contains an 8 GB logical volume. The installer would not allow you to remove either of the component physical volumes, since that would leave only 5 GB in the group for an 8 GB logical volume. If you reduce the total size of any logical volumes appropriately, you may then remove a physical volume from the volume group. In the example, reducing the size of the logical volume to 4 GB would allow you to remove one of the 5 GB physical volumes.

Make Logical Volume

Choose this option to create an LVM logical volume. Select a mount point, file system type, and size (in MB) just as if it were a standard disk partition. You can also choose a name for the logical volume and specify the volume group to which it will belong.

The Make Logical Volume dialog.

Note:

In this window we can make many type of partition which is listed in Mount Point option.Like:-

1. / – Root

Every single file and directory starts from the root directory.

Only root user has write privilege under this directory.

Please note that /root is root user’s home directory, which is not same as /.

2. /var – Variable Files

var stands for variable files.

Content of the files that are expected to grow can be found under this directory.

This includes — system log files (/var/log); packages and database files (/var/lib); emails (/var/mail); print queues (/var/spool); lock files (/var/lock); temp files needed across reboots (/var/tmp).

3. /usr – User Programs

Contains binaries, libraries, documentation, and source-code for second level programs.

/usr/bin contains binary files for user programs. If you can’t find a user binary under /bin, look under /usr/bin. For example: at, awk, cc, less, scp

/usr/sbin contains binary files for system administrators. If you can’t find a system binary under /sbin, look under /usr/sbin. For example: atd, cron, sshd, useradd, userdel

/usr/lib contains libraries for /usr/bin and /usr/sbin

/usr/local contains users programs that you install from source. For example, when you install apache from source, it goes under /usr/local/apache2.

4. /home – Home Directories

Home directories for all users to store their personal files.

For example: /home/john, /home/nikita

5. /opt – Optional add-on Applications

opt stands for optional.

Contains add-on applications from individual vendors.

add-on applications should be installed under either /opt/ or /opt/ sub-directory.

6. swap