lvm device not found in /dev/mapper

lvm device is missing. lvm Volume status is not available. Missing Volume.

If you are not able to find your logical volume (lvm device), check the status of the device or volume.
Run command

lvdisplay

If LV status is Not Available, it will not be listed in /dev/mapper or your lvm device directory.
Make the status available, Run command

vgchange -a y

It makes status available of all volumes.

Now the device will be visible in /dev/mapper or your lvm device directory.
Mount the device using

mount -t ext4 /path/of/the/lvm/device /path/of/mounted/location

Suppose I want to mount vg-lv_home in /home, I run

mount -t ext4 /dev/mapper/vg-lv_home /home

Now I can see all my files of the volume in /home

lvm commands not found

-bash: pvscan: command not found
-bash: lvdisplay: command not found
-bash: vgcreate: command not found
-bash: lvcreate: command not found
-bash: lvscan: command not found
-bash: pvdisplay: command not found
-bash: lvm: command not found

If you are using CentOS or fedora or RHEL and you are getting these errors again and again when you try to run lvm commands. It means lvm is not installed or corrupted on your system. Reinstall lvm again.

yum install lvm2

If it is not able to find lvm2 package and shows

No package lvm2 available.

It means your repositories do not have this package.
Enable appropriate repository like base, remi, rpmforge or epel and install it again.

If you have enabled all available repositories and still it shows "No package available."
Check the file /etc/yum.conf
The lvm2 package should not be there in exclude packages.
Repos do not list exclude packages and do not install them. If it is under exclude attribute, remove it and run install command again.
It should be installed.

Create Case insensitive databases and tables in mysql

Linux is case sensitive system. You can create Test or test or tesT files in same directory.
That's why you can create Test and teST both databases in mysql.
But if you do not want case sensitivity while creating databases and tables in mysql. Here is solution for you.

Add following attribute in the file my.cnf

lower_case_table_names = 1

Restart mysql.
It disables case sensitivity. Now you can not create linuxamination or Linuxamination or LinuXamination all three databases. You can create any one of three. Same rule is applicable for tables.

If you do not want this feature, remove this line or set the attribute 0.