Upgrading to DRBD 8.4 ===================== Linux kernel versions after 3.8 include DRBD 8.4, a new minor release with significant changes both in configuration and operation. An overview of the most important changes can be found at: http://www.drbd.org/users-guide-8.4/ap-recent-changes.html Configuration file changes -------------------------- A number of changes in the configuration file format are present in 8.4. They are outlined at: http://www.drbd.org/users-guide-8.4/s-recent-changes-config.html If you are upgrading from 8.3, please upgrade your configuration files to the new format. Unfortunately, due to the way backwards compatility is provided upstream, these options will not be understood by drbdadm if you boot a kernel with DRBD 8.3 (kernel versions before 3.8), so you will have to revert your changes if you want to use older kernels. Downgrading to DRBD 8.3 ------------------------ A device that has been attached or created using DRBD 8.4 will not work automatically under DRBD 8.3, due to changes in device metadata. In order to make your devices work with DRBD 8.3, you will have to do the following *before* booting the old kernel, to ensure that the metadata is clean: drbdadm down all drbdadm apply-al all More information can be found at: http://www.drbd.org/users-guide-8.4/s-downgrading-drbd84.html Participation in the usage count -------------------------------- The Debian package by default disables the participation in the DRBD usage count survey[0]. If you wish your system to be counted, change the 'usage-count' setting to 'yes' or 'ask' in /etc/drbd.d/common_global.conf. [0] http://www.drbd.org/usage/introduction0/