Hitachi HUS151473VL3800 Specifications - Page 271
Recommendations for System Error Log, Data Recovery Procedure
![]() |
UPC - 102645854861
View all Hitachi HUS151473VL3800 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 271 highlights
20.20.2 Recommendations for System Error Log The system error log should contain information about the Drive error that will allow recovery actions. The system error logs should contain all the error information returned in the sense data. At a minimum, the following information about each error occurrence should be logged. • Valid bit and error code (Sense byte 0) • Sense Key (Sense byte 2) • Information bytes (Sense bytes 3 through 6) • Command specific information (Sense bytes 8 through 11) • Additional Sense Code (Sense byte 12) • Additional Sense Code Qualifier (Sense byte 13) • Field Replaceable Unit (Sense byte 14) • Sense Key Specific (Sense bytes 15, 16, and 17) • Vender Unique error information (Sense bytes 20 through 23) 20.20.3 Data Recovery Procedure Statistically, most data error activity is noise related and has nothing to do with defects in the media. It is wrong for the system to assume that every data error reported occurred because of a defect in the media. It is also wrong for the system to assume that every data error that occurred because of a media defect rendered the Drive unusable. Recurring data error activity at the same physical location is an indication of a problem. The problem can be due to a media defect or magnetic damage. A media defect is physical damage to the recording capability of the media while magnetic damage is a defect in the bit pattern written to the media. In both cases, the error can be corrected without replacing the unit. The physical sector may require relocation. The Drive determines the need to reassign a sector. The Mode Select Page 1 option bit ARRE (See Section 17.10.3, "Mode Page 01 (Read/Write Error Recovery Parameters)" on page 114) set active allows the Drive to relocate recovered read data errors. Non recovered data errors or the ARRE bit being inactive will have additional sense codes returned to recommend reassignment of sectors. The need to reassign a sector should be infrequent. Sites not meeting error rate criteria are removed from use during SAT (Surface Analysis Test) in Drive manufacturing. With the exception of some early life SAT escapes (sites that were marginally missed during SAT), reassigning defective sectors should be rare. Frequent sector reassignment may be an (early) indication of another type of failure. Sector reassignments are monitored as part of the predictive failure analysis. When a threshold is exceeded, the Drive will notify the initiator that a scheduled service action is required. Drive soft error rates are based on extraneous random faults that are not predictable. Media defects discovered after the Drive completes manufacturing final test need to be relocated so that soft error rates are not influenced by predictable known error sites. Failure of the system to properly relocate defective media sites can have a direct influence on system throughput and drive error rates. Hitachi Ultrastar 15K147 SCSI Hard Disk Drive Specification 253
![](/manual_guide/products/hitachi-hus151473vl3800-specifications-fa60b78/271.png)