StoppedAt       time.Time          `msg:"stopTs"` // Time when rebalance-stop was issued.
	ID              string             `msg:"id"`     // ID of the ongoing rebalance operation
	PercentFreeGoal float64            `msg:"pf"`     // Computed from total free space and capacity at the start of rebalance
	PoolStats       []*rebalanceStats  `msg:"rss"`    // Per-pool rebalance stats keyed by pool index
}