Processor resources are shared between all running processes based upon their priority level. Since the S.M.A.R.T. test is a low-priority level service, it might be stuck at 90% completion if the system is busy running other higher priority services at the same time. To resolve this issue, you can do any of the following:
- If you want the S.M.A.R.T. test to run more smoothly, you can schedule the test for a time when the system is less busy. You can go to DSM > Storage Manager > HDD/SSD > Test Scheduler to set a new schedule for the S.M.A.R.T. test.
- If you do not wish to postpone the S.M.A.R.T. test, you can go to DSM > Resource Monitor > Task Manager > Services to see which packages or services are hogging up system resources. Temporarily stop running these packages or services, and wait for the S.M.A.R.T. test to complete.
- You can also connect your drives to your personal computer and use other diagnostic tools to check the health status of the drives (Tutorial).