First we need to explain what seamless migration means. There are several ways. Some may say, it means drag and drop a folder from local to HP Cloud and then forever works there from the cloud. This is one of the way. As an analogy, you want to get on a one-way plane to the cloud, move data there and never come back.
More realistically, you want to mirror everything local to the cloud, also maintain this two way sync structure, so everything changed local will continue to move to the cloud. Everything changed in the cloud will be mirrored back to local. This in Gladinet terminology, you attached a local folder to the cloud.
Once you attached a local folder to the cloud, the content is migrate to the cloud in the background. Also because it is attached to the cloud, you can do random access to the local folder, from the cloud. This is especially for big folder such as migrating 500G to the cloud, when you don’t want to have any downtime for the migration. So it is a seamless migration.