I breify described what an lvm here http://sneekygeekers.com/2014/02/14/linux-and-logical-volume-management/.Some installers have support this without needing any manual configuration, however as of 04/2014 it still needs to be done manually for lmde.
If you haven’t already download the iso from http://blog.linuxmint.com/?p=2577 and burn it to a disk or use a usb device depending on your favourite method.
For this example I am using the 201404 Mate 32bit ISO.
This is what I am starting with. I am going to use /dev/sda3, /dev/sda5 and /dev/sda7, mainly to show that lvm’s can span more then one partition, can be inside and out of an extended which also do not need to be next to each other on the same disk , I could have also chosen another parition on another disk but I didnt have a spare one.
Open a terminal, sudo pvcreate /dev/sda3 /dev/sda5 /dev/sda7
sudo pvscan or sudo pvdisplay for more information outputs the physical volumes.
Create a volume group with sudo vgcreate my_vol_group , this can be anything, I used my_vol_group
sudo vgdisplay will output volume groups
Create a logical volume for a partition I used sudo lvcreate -l 15357 -n logical_vol1 my_vol_group , the logical_vol1 is what I chose , you can choose something else , I also used all of the available space because I only want to create one partition
sudo lvdisplay outputs the logical volumes.
I did sudo mkfs.ext4 /dev/my_vol_group/logical_vol1 you can of course use a different partiton type , however ext4 is the most common. Do the same for any other partitions you wish to create
sudo blkid outputs the current partitining layout with uuid numbers
Now create /target and mount the partition there (make sure you use /target, it is important later) with sudo mkdir /target && sudo mount /dev/mapper/my_vol_group-logical_vol1
Now start the installer. The first dialogue is to select language
Username, Password and Hostname
At the partitioning screen select “Manually mount partitions”
Since the partition is already mounted at /target we can go foward
Install grub to the MBR unless you know you do not need to
Summary of actions
Installing , this process could take awhile
The installation is paused so we can configure what we need
I am not using a chroot here to create the fstab entries , but if you desire to do other tasks at the same time you can do so now. To create the fstab entries sudo pluma /etc/fstab (for mate) or sudo gedit /etc/fstab (cinnamon) and if using alt-f2 instead of sudo use gksudo
Using the output of sudo blkid create the entries for / and swap, also add any other entries you desire
Once everything you wish is done click foward
The installation process continues and finalizes
When it is finished reboot when you are ready