if (isSlaveDead(slaveId)) {
slaveManager.removeDead(slaveId);
}
SingularitySlave newSlave = new SingularitySlave(slaveId, host, rackId);
slaveManager.save(newSlave);
return new SaveResultHolder(Optional.of((SingularityMachineAbstraction) newSlave), SaveResult.NEW);
}