Vitess maintainer here. While Vitess can still use gh-ost, the recommended way is to use Vitess' internal VReplication mechanism. With this, your can throttle, pause, resume, cancel, retry, revert a migration, as well as auto-resume from failover (migration continues from point of interruption once a new primary is instated).
Vitess throttling is by default based on replication lag, but you can use different metrics, such as load average, or indeed multiple metrics combined, to define what constitutes a load.
Vitess throttling is by default based on replication lag, but you can use different metrics, such as load average, or indeed multiple metrics combined, to define what constitutes a load.