11.2 Troubleshooting the Hardware Box
11.2.10 Secondary storage devices
Hard Drives
Some computers will be configured with two different hard drives. Configuring a computer with two hard drives increases space for backups and storing data. If two hard drives are configured on the same ribbon cable, they must have a master slave relationship. During normal operation, the computer will boot from the OS loaded on the hard drive that is set to master. The master drive will manage the slave drive (drive with the jumper set to slave) once the computer boots up. The hard drive that is set to slave provides extra storage capabilities.

When two drives are installed, the majority of problems will result from improperly set jumpers or incorrect BIOS settings. Hard drive manufacturers decide the jumper settings, so the technician will need to consult the hard drive manual or the manufacturer website for specific details. However, each drive has to be set to master, slave, or cable select. The hard drive that contains the OS will need to have its jumpers set to master. The secondary drive will need to be set to slave.

Cable Select (CSEL) is an option that decides master/slave hard drive relationships based on the position of the drive on the IDE cable. In order for Cable Select to work properly, each device must have its jumpers set to CSEL, CSEL cabling must be used, and the host interface connector must support CSEL. If problems are being experienced with a dual hard drive system, verify that the jumper settings are correctly set. Devices need to be set to Master or Slave, or both set to Cable Select (CSEL).