Problem
Viewing hardware configuration and detection using Discover.exe
Solution
Backup Exec has included a standalone hardware discovery tool called Discover.exe which outputs detailed attributes of backup devices that are attached to the server. Since Discover is a standalone application, it can be downloaded and run on any Windows server. This tool can be used by users looking to upgrade to Backup Exec, or for troubleshooting hardware issues in older versions of Backup Exec. See Related Documents for download information.
Running the discover tool:
Discover.exe is a command-line utility and is located in the install directory of Backup Exec (by default C:\ Program Files\Veritas\Backup Exec).
To run Discover.exe, it is very important that the Backup Exec services be stopped. Discover will be blocked access from Medium Changers if the Backup Exec services are running. Discover will, by design, attempt to reserve any backup device that is attached to the server in an effort to query the device and determine its attributes.
After stopping the services, simply run Discover.exe from a command prompt and discover will output the attributes from all SCSI based devices on the server.
Reading the Output:
Discover will output a list of any SCSI based device that attached to the local system, and the attributes of those devices. The devices are listed in the following order:
ByName: MediumChanger - all medium changers attached to the system.
ByName: Changer - all changers attached to the system.
ByPort: Scsi - lists of all SCSI devices. Contains Inquiry Data for non-tape devices attached via SCSI. SCSI ports with tape devices are left blank in this section.
ByGuid: Tape - GUID of the tape drives.
ByGuid: Changer - GUID's the Changer
ByGuid: ChangerIomega - GUID for any IOMEGA Changer.
ByGuid: CDRom- GUID for CDRom devices.
Common values for all devices
System Page Size
##:##:##:## is the physical address of the device (Port : Bus : Target : Lun), followed by the Device Name
INQ 00 - The Primary Inquiry String of the device
INQ cc - Vendor-Specific Inquiry String (Compaq)
INQ dc - Vendor-Specific Inquiry String (Dell)
INQ 83 - Serial Number of the device (contains inquiry data)
INQ 80 - Serial Number of the device
TUR 00 23a00 - Results of "Test Unit Ready" command *
RES 00 00 00000 - Results of "Reserve" command *
REL 00 00 00000 - Results of "Release" command *
* See 'Interpreting Command Results' below for information on understanding these results.
Values for Medium Changers only
For each of these values, the first 4 digits are the element addresses of each component. The single digit following the element address contains the number of actual elements that are present.
STE - Storage Transfer Element - the number of slots the library has.
IEE - Import/Export Element - the number of portal slots the library has.
DTE - Data Transfer Element - number of tape drives contained in the library.
Underneath the Data Transfer Element, for each drive discovered you will see a single digit element number followed a serial number in double quotes. This serial number is how the library and tape drive are linked together. Consider the following:
DTE 0080 2
0 "0000910023"
1 "0000909939"
This indicates that this library has two tape drives, 0 and 1, and their serial numbers are 0000910023 and 0000909939 respectively.
If the DTE contains an empty set of quotes, or random ASCII characters, this is most likely indicative of a device that is not serializing. Some older legacy tape drives and libraries do not serialize.
Values for Tape Drives only
BUS - The BUS Type for the tape drive
MAX ### bytes ### pages - The max number of bytes and pages that can be included in a SCSI command.
Interpreting Command Results
For the Test Unit Ready (TUR), Reserve (RES), and Release (REL) commands, the last 5 characters listed contain SCSI response information. Discover attempts these commands on each device whenever it is run, and will log the results of those commands.
If the response field is all 0's, that is 00000, then the command completed with a successful SCSI status.
If the response field contains information, then that indicates that the particular command did not complete successfully and resulted in a SCSI error known as a "Check Condition." Consider the following TUR command:
The above error on the TUR above is a common check condition that is seen on tape drives. To translate the error will require a basic understanding of SCSI commands and check conditions.
The error 23a00 is broken down by Sense key (2), Additional Sense Code - ASC (3a), and Additional Sense Code Qualifier - ASCQ (00).
Sense Key 2 = NOT READY
ASC/ASCQ 3a/00 = MEDIUM NOT PRESENT
This check condition occurs because there is no tape in the drive. While this is considered an error by SCSI standards, it is not indicative of any hardware failure. Had the sense key been 4, this would have been indicative of a hardware failure.
A full list of all Sense Keys can be found here:
http://www.t10.org/lists/2sensekey.htm
A numerical list of ASC/ASCQ can be found here:
http://www.t10.org/lists/asc-num.htm
Example detection errors:
The follow are types of errors messages that can be seen when running Discover.exe:
CreateFile on \\.\Tape0 failed, 32 - The process cannot access the file because it is being used by another process.
ByName: MediumChanger
CreateFile on \\.\MediumChanger0 failed, 5 - Access is denied.
ByName: Changer
CreateFile on \\.\Changer0 failed, 170 - The requested resource is in use.
These errors can occur when another application or process is denying access to the device, or if the device itself is malfunctioning. It can also occur when the Backup Exec services are running.
If you see errors in discover, and the Backup Exec services are in fact stopped, then proceed to troubleshoot the hardware. Consider performing a power cycle of the hardware and media server, and running a SCSI trace using a tool such as Tracer.
See Related Documents for more information on troubleshooting hardware and using tools such as tracer.
Example output from Discover.exe:
Below is the expected output from a server with a properly configured Dell Powervault 124T library with an LTO3 drive:
System Page Size: 4096
ByName: Tape
03:00:06:00 01 -- \\.\Tape0
INQ 00 "IBM ULTRIUM-TD3 6B20"
INQ cc ""
INQ dc ""
INQ 83 "IBM ULTRIUM-TD3 1210407620"
INQ 80 "1210407620"
TUR 00 23a00
RES 00 00 00000
REL 00 00 00000
BUS SCSI(1)
MAX 0xffffffff bytes 0x41 pages
ByName: MediumChanger
03:00:06:01 08 -- \\.\MediumChanger0
INQ 00 "DELL PV-124T 0060"
INQ cc ""
INQ dc "DELL PV-124T 0060"
INQ 83 "DELL PV-124T CK8JB30213"
INQ 80 "CK8JB30213"
TUR 00 00000
RES 00 00 00000
REL 00 00 00000
MTE 0000 1
STE 0100 16
IEE 0000 0
DTE 0020 1
0 "1210407620"
ByName: Changer
ByPort: Scsi
02:00:06:01 08 -- \\.\Scsi2:
03:00:06:01 08 -- \\.\Scsi3:
05:00:00:00 00 -- \\.\Scsi4:
INQ 00 "DGC RAID 5 0326"
INQ cc ""
INQ dc ""
INQ 80 "APM00073400040"
ByGuid: Tape
03:00:06:00 01 01 \\?\scsi#sequential&ven_ibm&prod_ultrium-td3&rev_6b20#6&3b682dcf&0&060#{53f5630b-b6bf-11d0-94f2-00a0c91efb8b}
ByGuid: Changer
ByGuid: ChangerIomega
ByGuid: CDRom
00:00:00:00 05 00 \\?\ide#cdromteac_cd-224e-n__________________________c.aa____#5&117b794a&0&0.0.0#{53f56308-b6bf-11d0-94f2-00a0c91efb8b}
INQ 00 "TEAC CD-224E-N C.AA"
INQ cc ""
INQ dc ""
INQ 80 ""
If you have difficulty interpreting the data gathered by Discover, please contact Veritas Technical Support.
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