Question: Back in the days of PATA hard drives, a person used jumpers on the drive to indicate whether the drive was the master or the slave of the channel, or to let the cable select which drive was which.
SATA drives are one-per-channel, one-per-cable, etc.
What are the jumpers for on SATA hard drives?
Answer: Some SATA drivers have jumpers for extra features, or for troubleshooting.
Example from the manual of a Western Digital SATA disk:
Set the Jumpers
The default setting for WD SATA harddrives varies depending on the model.To determine the default setting foryour drive, look at the drive label onthe top of the drive.
DO NOT changethe default setting if you intend touse the drive in a desktop computer.
Change the jumper settings ONLY if youintend to use the drive in anenterprise storage environment. Formore ?information on these advancedsettings, obtain the full version WDSATA Installation Guide atsupport.wdc.com.
SSC_DIS Mode(Default) Enable or disable thespread spectrum clocking feature.Default setting is disabled.
OPT1 Only for factory use.
OPT2 Only forfactory use.