The default replica count can be changed in the setting.
Also, when a volume is attached, the user can change the replica count for the volume in the UI.
Longhorn will always try to maintain at least given number of healthy replicas for each volume.
After v0.6.0, when the user attaching the volume from Longhorn UI, there is a checkbox for
Maintenance mode. The option will result in attaching the volume without enabling the frontend (block device or iSCSI), to make sure no one can access the volume data when the volume is attached.
It’s mainly used to perform
Snapshot Revert. After v0.6.0, Snapshot Reverting operation required volume to be in
Maintenance mode since we cannot modify the block device’s content with the volume mounted or being used, otherwise it will cause filesystem corruptions.
It’s also useful to inspect the volume state without worry that the data can be accessed by accident.