Using SGMON.EXE to capture hardware SCSI Trace information

Article:TECH63629  |  Created: 2009-01-02  |  Updated: 2011-09-07  |  Article URL http://www.symantec.com/docs/TECH63629
Article Type
Technical Solution


Environment

Issue



Using SGMON.EXE to capture hardware SCSI Trace information


Solution



Using SGMON.EXE to capture hardware SCSI Trace information
 
Starting with Backup Exec version 12.0, the Backup Exec debug utility SGMON can be configured to perform a hardware SCSI trace. Performing this level of debugging will capture the same information captured by Tracer.exe, however SGMON comes with more flexible options, such as the ability to debug on a schedule.
 
To capture a SCSI trace with SGMON, launch SGMON and click on Tools > Settings > Agents > Device and Media, and place a check mark next to 'Enable Verbose Logging.' Then, from the SGMON UI, place a check mark next to 'Device and Media'
 
NOTE:  Due to the inherit nature of SCSI and the high number of commands sent to and from SCSI-based devices, SGMON logs configured with Verbose Device and Media Debugging enabled can become quite large rather quickly and very easily writes many Gigabytes worth of data. If SGMON is saving the logs on the operating system volume then it can easily fill the operating system volume.
 
For that reason, it is best to try to reproduce the problem in as short an operation as possible to minimize the size of the SCSI trace, as well as configure SGMON to save logs on a volume that does not contain the operating system.
Changing the Debug Log output location:
Warning: Incorrect use of the Windows registry editor may prevent the operating system from functioning properly. Great care should be taken when making changes to a Windows registry. Registry modifications should only be carried-out by persons experienced in the use of the registry editor application. It is recommended that a complete backup of the registry and workstation be made prior to making any registry changes.
 
The output location for the debug logs can be set in following registry key:
 
HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Backup Exec For Windows\Backup Exec\Debug\Path
 
Change the path to the desired location, and then restart SGMON for the changes to take place. Since Verbose Device and Media debugging will generate such large amounts of debug information, it would be advised to keep this location local to the media server.
 
 
NOTE: Changing this setting will also change the path to ALL debug logs and not just the SGMON debugs logs.
 
 
Reading SCSI output in SGMON:
 
The SCSI trace is logged by SGMON under PVLSVR.EXE and is noted by DeviceIo: SCSI.
 
Below is sample output from a single SCSI command in SGMON:
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: CDB 00:00:05:00 Start 12:08:53.128 End 12:08:53.128
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: ASPI Status SCSI_COMPLETED_WITHOUT_ERROR
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: Target Status NO_TARGET_STATUS
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: HBA Status HOST_NO_ERROR
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: Function SRB_FUNCTION_EXECUTE_SCSI
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI:
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: Raw CDB
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: 1A 08 0F 00 14 00                               ......
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI:
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: CDB Operation MODE_SENSE6
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI:  LUN 0
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI:  DBD True
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI:  Page Code Current Values(0)
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI:  Alloc Length 20
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI:  Control 0x00
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: Data
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: 13 00 10 00 0F 0E 40 80 00 00 00 10 00 00 00 10 ......@.........
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI: 00 00 00 00                                     ....
PVLSVR:   [09/26/08 12:08:53] [5412]     DeviceIo: SCSI:


To understand the various SCSI commands, please see the related documents on using TRACER.EXE to perform a SCSI trace.

 

 



Legacy ID



308975


Article URL http://www.symantec.com/docs/TECH63629


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