Working with a Logical Volume Manager

The Logical Volume Manager creates symbolic links to each logical volume's block device, from a directory path in the form:

/dev/<volume group>/<volume name>

MapR needs the actual block location, which you can find by using the ls -l command to list the symbolic links.

Make sure you have free, unmounted logical volumes for use by MapR:
- Unmount any mounted logical volumes that can be erased and used for MapR.
- Allocate any free space in an existing logical volume group to new logical volumes.
Make a note of the volume group and volume name of each logical volume.
Use ls -l with the volume group and volume name to determine the path of each logical volume's block device. Each logical volume is a symbolic link to a logical block device from a directory path that uses the volume group and volume name:
```
/dev/<volume group>/<volume name>
```
The following example shows output that represents a volume group named mapr containing logical volumes named mapr1, mapr2, mapr3, and mapr4:
```
# ls -l /dev/mapr/mapr*
lrwxrwxrwx 1 root root 22 Apr 12 21:48 /dev/mapr/mapr1 -> /dev/mapper/mapr-mapr1
lrwxrwxrwx 1 root root 22 Apr 12 21:48 /dev/mapr/mapr2 -> /dev/mapper/mapr-mapr2
lrwxrwxrwx 1 root root 22 Apr 12 21:48 /dev/mapr/mapr3 -> /dev/mapper/mapr-mapr3
lrwxrwxrwx 1 root root 22 Apr 12 21:48 /dev/mapr/mapr4 -> /dev/mapper/mapr-mapr4
```
Create a text file /tmp/disks.txt containing the paths to the block devices for the logical volumes (one path on each line). Example:
```
$ cat  /tmp/disks.txt
/dev/mapper/mapr-mapr1
/dev/mapper/mapr-mapr2
/dev/mapper/mapr-mapr3
/dev/mapper/mapr-mapr4
```
Pass disks.txt to disksetup.