HPE ProLiant ML30 Gen10 Plus Maintenance And Service Manual page 152

Amber/blue LED—Managed by the drive backplane in conjunction with the storage controller and is used to indicate drive status.
Green LED—Managed by the drive itself and indicates the drive activity.
LFF low-profile drive carrier LFF low-profile drive carrier
The LFF low-profile drive carrier supports hot-plug SAS and SATA drives .
SFF basic drive carrier SFF basic drive carrier
The SFF basic drive carrier supports hot-plug SAS and SATA drives .
HPE ProLiant ML30 Gen10 Plus Server Maintenance and Service Guide 152