# Configuring Logical Volume Manager

Control Center application data is managed by a device mapper thin pool created with Logical Volume Manager (LVM). This procedure adjusts the LVM configuration for mirroring by DRBD.
Perform this procedure on the primary node and on the secondary node.
1. Log in to the host as root, or as a user with superuser privileges.
2. Create a backup copy of the LVM configuration file.
cp -p /etc/lvm/lvm.conf /etc/lvm/lvm.conf.bak
3. Open /etc/lvm/lvm.conf with a text editor.
4. Edit the devices/filter configuration option to exclude the partition for Control Center application data.
1. Search for the following text, which marks the beginning of the section about the devices/filter configuration option:
# Configuration option devices/filter
2. At the end of section, remove the comment character (#) from the beginning of the following line:
# filter = [ "a|.*/|" ]
The line to edit is about 30 lines below the beginning the section.
3. Exclude the partition for Control Center application data.
Replace App-Data-Storage with the path of the block storage designated for Control Center application data:
filter = ["r|App-Data-Storage|"]
For example, if the value of App-Data-Storage in your environment is /dev/sdd, the result should look like the following line:
filter = ["r|/dev/sdd|"]
5. Edit the devices/write_cache_state configuration option to disable caching.
1. Search for the following text, which marks the beginning of the section about the devices/write_cache_state configuration option:
# Configuration option devices/write_cache_state
2. Set the value of the write_cache_state option to 0.
The result should look like the following line:
write_cache_state = 0
1. Search for the following text, which marks the beginning of the section about the global/use_lvmetad configuration option:
# Configuration option global/use_lvmetad
The line to edit is about 27 lines below the beginning the section.
2. Set the value of the use_lvmetad option to 0.
The result should look like the following line:
use_lvmetad = 0
7. Save the file and close the text editor.
8. Delete any stale cache entries.
rm -f /etc/lvm/cache/.cache
9. Restart the host.
reboot