SCSI Test Unit Ready Command
Encyclopedia
The SCSI Test Unit Ready command is used to determine if a device is ready to transfer data (read/write), i.e. if a disk has spun up, if a tape is loaded and ready etc. The device does not perform a self-test operation. See the Send Diagnostic command
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The CDB
structure is:
The device will then return either good status or a check condition
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SCSI Send Diagnostic Command
The SCSI Send Diagnostic command is used to instruct a target device to perform a self-test on a specific LUN. The CDB structure is:The special parameter fields in the CDB have the following meaning:*PF - Page Format:...
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The CDB
SCSI CDB
In SCSI computer storage, commands are sent in a Command Descriptor Block .Each CDB can be a total of 6, 10, 12, or 16 bytes, but later versions of the SCSI standard also allow for variable-length CDBs. The CDB consists of a one byte operation code followed by some command-specific parameters.A...
structure is:
| bit→ ↓byte |
0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|---|
| 0 | Operation Code = 0x00 | |||||||
| 1 | LUN | Reserved | ||||||
| 2 | Reserved | |||||||
| 3 | ||||||||
| 4 | ||||||||
| 5 | Control | |||||||
The device will then return either good status or a check condition
SCSI check condition
In computer terminology, a Check Condition occurs when a SCSI device needs to report an error.SCSI communication takes place between an initiator and a target. The initiator sends a command to the target which then responds. SCSI commands are sent in a Command Descriptor Block...
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