Today, with the launch of M7i instances, customers can attach up to 128 EBS volumes to an EC2 instance. By comparison, previous generation M6i instances allow up to 28 EBS volume attachments to an EC2 instance. The higher volume attachment limit enables customers to increase storage density per EC2 instance, so that they can host larger applications per instance or reduce total compute cost by improving their resource utilization. With this launch, customers can also take crash-consistent snapshots for up to 128 EBS volumes attached to a single EC2 instance.
Source:: Amazon AWS