SCSI Hard Drives- Failure and Recovery

SCSI (Small Computer System Interface) is an intelligent interface.It hides the complexity of physical format. Every device attaches to the SCSI bus in a similar manner. SCSI hard drives are faster than the others. These hard drives are often used with servers that require high performance throughput. It can happen with these hard drives that they may fail to perform with required rate.

Cause Explanation

The SCSI hard drives can’t start up when there is a physical failure. When the computer system is powered on, SCSI BIOS gets the drive control from system BIOS. This SCSI BIOS sends �Start Unit Request’ to the SCSI devices including SCSI hard drive so that they may start and spin up. SCSI BIOS gets �Start Unit Request Completed’ along with some additional information from drives in return. In case the task completion command is not received in a specific interval of time by SCSI BIOS, it sends back an error message that might occur due to a hard drive failure:

“Start Unit Request Faild”

There could the following reasons for this error message:

1. High Condensation and Electronic Failure: At high speed environment, the major concern with such hard drives is heat. Although SCSI hard drive has a great resistance to heat but at the time of power off and condensation occurs, they are hard drive electronics that suffer the most. The electronic components may break down due to high stress conditions making a hard drive worthless.

In such cases,  hard drive recovery is possible to the maximum extent as platters don’t suffer to the corresponding damage.


2. Mechanical Failure: Hard drive can remain functional and tolerate vibrations until they strike read/write head. The head crash can be detected by strange noises.


This problem can be resolved by hard drive replacement after recovery service. At the same time there can be other, though minor, solutions too:

1 The user can disabl the Unit Request confirmation from drive.


2 The user can make a jumper setting so as to ignore SCSI BIOS process. The drive can be set to auto-start in which system starts as it gets power.


However if these solutions are not possible or fail, the most appropriate solution is Hard Disk Recovery , using Hard Drive Recovery Software which is meant to extract the lost data .

Stellar Information Systems Limited is a leading company providing hard drive recovery software service since years. The company is best known to offer Class 100 Clean Room facility, advanced set of data extracting procedures and expert technicians’ assistance. Stellar’s Hard Drive Recovery is provided for interfaces including SCSI, IDE (PATA) and SATA.