SCSI Log Sense Command
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The SCSI Log Sense command is used to obtain current data from log pages in a SCSI target device. The CDB structure for the Log Sense command is:
The CDB structure is:
| Bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|---|
| +0 | Operation Code = 0x4D | |||||||
| +8 | LUN Reserved | PPC | SP | |||||
| +16 | PC | PAGE CODE | ||||||
| +24 | SUBPAGE CODE | |||||||
| +32 | Reserved | |||||||
| +40 | PARAMETER POINTER | |||||||
| +48 | ||||||||
| +56 | ALLOCATION LENGTH | |||||||
| +64 | ||||||||
| +72 | Control | |||||||
The special parameter fields in the CDB have the following meaning:
- PPC - Parameter Pointer Control - if this is one then the target returns a log page with parameter code values which have changed since the last Log Select command or Log Sense command. If PPC is zero then all bytes are returned.
- SP - Save Parameters - if this is one then the target should save all saveable log parameters to a non-volatile memory or media area.
- PC - Page Control - this indicates which type of values should be returned:
- 00 - Current Threshold Values
- 01 - Current Cumulative Values
- 10 - Default Threshold Values
- 11 - Default Cumulative Values
- Parameter Pointer indicates the first parameter code to be returned.
- Allocation Length in bytes
If the Parameter Pointer is zero and the PPC is zero and the Allocation Length is high enough then all parameters are returned.
