persistent_data.yml controls which mcMMO mob-tracking flags are persisted to disk (NBT data written when a chunk unloads) versus kept in memory only. Default values can be viewed on GitHub.
Changes require a full server restart.
mcMMO tags certain mobs with metadata to prevent XP exploits (e.g., a mob that came from a spawner should give 0 XP). When a mob's flag is not saved to disk (Saved_To_Disk: false), the flag lives only in memory — if the server restarts or the chunk unloads, the mob "forgets" its tag.
Enabling persistence (Saved_To_Disk: true) solves this but adds a small disk I/O cost every time a chunk containing that type of entity is unloaded. Servers with very large numbers of a given entity type (especially endermen or spawner mobs) should monitor TPS before enabling persistence for those categories.
| Key | Default | Description |
|---|---|---|
MOB_SPAWNER_MOB |
false |
Mobs that spawned from a mob spawner. Gives 0 XP by default. |
EGG_MOB |
false |
Mobs spawned from spawn eggs. Gives 0 XP by default. |
NETHER_PORTAL_MOB |
false |
Mobs that entered via a nether portal. Gives 0 XP by default. |
COTW_SUMMONED_MOB |
true |
Pets summoned by Call of the Wild. Persistent by default because there are rarely many of them. |
PLAYER_BRED_MOB |
false |
Mobs bred by players. Gives normal XP by default; adjust in experience.yml. |
EXPLOITED_ENDERMEN |
false |
Endermen that arrived via the Enderman/Endermite exploit. Gives 0 XP. |
PLAYER_TAMED_MOB |
false |
Mobs tamed by players. Gives 0 XP, not currently adjustable. |
| Key | Default | Description |
|---|---|---|
mcMMO_Region_System.Enabled |
true |
Track which blocks were placed by players. Disabling this enables XP exploits such as player-placed block duplication farms. Do not disable. |
The region system uses its own highly optimised file system separate from Spigot's NBT API, so it carries negligible performance cost.