With the Hybrid Cloud Extension (HCX) solution, customers can migrate workloads immediately or have them scheduled at a later date and time of their choosing. Most customers will most likely not migrate all their workloads at once, but instead migrate them in different phases or waves based on their own internal schedules. The HCX "Migration" tab in the vSphere Client is a great place to get an overview of all the active, failed, planned and completed migrations and you can get additional details for each migration such status, percentage, amount of data transferred, etc.
Having said that, you probably also do not want to just sit there and constantly watch for progress, especially if something fails. The good news is that HCX already includes some default vCenter Alarms that are generated when a migration fails. There is one for vMotion/Cloud Motion, Cold Migration as well as Bulk Migration and currently these alarms only trigger a UI indication that something is wrong using the red critical icon on the VM in question.
Since these are vCenter Alarms, you also have the option of adding additional actions such as sending an email alert to a particular user or group, an SNMP trap which can then be monitored by your operations team or even run a command within the vCenter Server. Simply updating the default alarm which is defined at the vCenter Server level, you can proactively get notified when an HCX migration fails without having to constantly watch the UI. You may have also noticed the alarm definition is using a numeric ID which is highlighted in the screenshot above. This maybe useful if you wish to leave the default alarms alone and create a brand new alarm, you just need to use those IDs.
Another useful scenario to consider is getting notifications for a successful migration which can then help with transitioning users to the new VM running on VMC or even trigger automated VM and application verification before end users are even notified. Along these similar lines, you can imagine another scenario to consider is with using Bulk Migration and/or Cloud Motion with vSphere Replication. Both methods initially start off by replicating the VM's data from the source vCenter Server to the destination vCenter Server and then either a Cold Migration or vMotion is performed based on the configured scheduled.