Btrfs balance schedule changed unexpectedly

SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP3
SUSE Linux Enterprise Micro 5.5
SUSE Linux Enterprise Micro 5.4
SUSE Linux Enterprise Micro 5.3

The balance schedule changed unexpectedly when editing the file /etc/sysconfig/btrfsmaintenance or when applying a btrfsmaintenance package update.

If the btrfs balance schedule has changed unexpectedly, then editing the appropriate lines in /etc/sysconfig/btrfsmaintenance can be done to reset the schedule to the desired frequency e.g.:

     BTRFS_BALANCE_PERIOD="monthly"

The syntax used for the variable can be a simple word as shown above or can be more complex. Examples can be found in the "Calendar Events" section of the systemd.time man page.

The balance timer configuration stored in /etc/sysconfig/btrfsmaintenance is initially not active. It becomes active by editing /etc/sysconfig/btrfsmaintenance or updating the btrfsmaintenance rpm. If the current balance timer schedule does not match the schedule defined in the /etc/sysconfig/btrfsmaintenance file, then the balance schedule can change.

This problem should only happen once on any given server, either when the /etc/sysconfig/btrfsmaintenance file is edited for the first time, or the first time that the btrfsmaintenance package is updated. After this, the server's btrfs balance schedule should always be dictated by what is present in the /etc/sysconfig/btrfsmaintenance file.

The default btrfs balance schedule is monthly.
The default btrfs balance schedule defined in the /etc/sysconfig/btrfsmaintenance file is weekly.

It is possible to avoid any unwanted change to the balance schedule by stopping the btrfs watcher process before applying any btrfsmaintenance package update and restarting it after patching e.g.:

     # systemctl stop btrfsmaintenance-refresh.path
     # rpm -Uvh btrfsmaintenance-<version>.noarch.rpm
     # systemctl start btrfsmaintenance-refresh.path

The btrfsmaintenance 'watcher' process (btrfsmaintenance-refresh.path):
The purpose of this systemd unit process is to watch for changes made to the /etc/sysconfig/btrfsmaintenance configuration file and then trigger a process to reflect those changes in the btrfs scrub, balance, trim and defragment related maintenance tasks/units.

Note:  Due to the same issue laid out in the cause section of this document, it may be possible for a 'disabled' btrfs balance schedule to again become active. In this event, manual intervention will be required to disable the balance schedule.

See related TID:    000021692 Multiple btrfs balance schedules are present
Master btrfs TID:  000018779 BTRFS Master TID