Storage Spaces driver.
Symptoms of this issue:
- Hard drive activity light solid on
- Occasional disk hangs
- Event ID 129 in Windows logs storahci “Reset to device, \Device\RaidPort0, was issued.”
Fix:
- Go to Power Options > Advanced > PCI Express > Link State Power Management and set it to Off.
- Reboot the server
Source: Event ID 129 – storachi – Reset to device, \Device\RaidPort0, was issued. (blogs.technet.com)
Fully resolved the issue for me.