‘Start Unit Request Failed’ Hard Drive Error and Recovery

Published: 04th April 2009
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SCSI (Small Computer System Interface) hard drives possess better performance due to their speed in terms of throughput and rpm (rotations per minute) rating. These hard drives are often used with servers, RAID and JBOD arrays and workstations that require high performance. But sometimes hard drive failure may affect our business critical operations due to drive health issues. Such crashes occur due to hard drive fatigue, component failure and external factors that require Data Recovery service as the solution.

Error Explanation

SCSI hard drives fail to start up when experience 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. Upon successful completion of task, SCSI BIOS gets 'Start Unit Request Completed' plus some additional information from drives in return. But if this task completion command is not received in a specific interval of time by SCSI BIOS, it returns an error message that might occur due to hard drive failure:

"Start Unit Request Failed"


• High Condensation and Electronic Failure: In high throughput environment, the major concern with such hard drives is heat. Though SCSI hard drives offer good resistance to heat but when the system is powered off and condensation occurs due to extreme heat, hard drive electronics suffer the most. The electronic components may break down due to high stress conditions making a hard drive useless.

• Mechanical Failure: Hard drives can remain functional and tolerate vibrations till the read/write head works fine. The head crash is characterized by strange noises. Apart from it, other internal failures also create a need for Data Recovery service preferably through Clean Rooms.

The above error message occurs due to hard drive failure and drive recovery service can take care of your precious data by extracting all your data files from the hard disk. But there are other solutions as well, which are:

• 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.

• User can disable the Unit Request confirmation from drive.

After we suitably apply these procedures, we can get enough time for data backup. However if these are not possible or fruitful, the most appropriate solution is to go for Hard Disk Recovery which is meant to extract lost data under expert supervision and through certified Clean Rooms.

Stellar Information Systems Limited is the number one company in providing high quality Data Recovery service since 1993. The company provides exhaustive Hard Drive Recovery through Class-100 Clean Room facility, advanced set of data extraction procedures and expert professionals. Stellar's Hard Disk Recovery is provided for interfaces including SCSI, SATA, EIDE/ATA-2 and IDE.

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