HP 27115A Installation Manual

NoteSummary of Trouble Trees Operation. Both trouble tree sections (10and 11) run four separate tests sequentially:1. Loopback on the PCA.2. Loopback to the disk drive directly connected to the HP-FL peA.3. Loopback to a target disk (anyone of the drives on the PBus).4. Loopback through the buffer on the target drive.The target drive is the drive you specify when running the diagnostic.If any of the tests fails, the section stops and reports it. Although it is possiblefor more than one error to exist on the HP-FL subsystem, it is unlikely.If there is a problem, suspected causes are displayed in the order of likelyoccurrence. Table 3-2 shows an example. We ran a test of the diagnosticprogram by inducing faults into a fiber-optic link system. The table shows theresults of this test. For each of the faults, it gives the number of suspectedcauses reported by the diagnostic, and the sequence number of the actual cause.Table 3-2. Examples from Testing Sections 10 and 11Drive Number Actualconfiguration Fault induced for the test of causes cause ofreported faultSingle Drive power switched off 4 firstSingle Incorrect drive address 3 firstSingle PBus terminators missing 3 firstSingle Fiber-optic cable not connected 4 secondSingle Cable fibers connected backwards 4 secondMultiple Power switched off on target drive 4 firstMultiple Incorrect target drive address 4 thirdMultiple PBus terminators missing 4 firstSection 12. ON-SITE TROUBLE TREEThis section is instructional and guides you through a troubleshooting procedureusing decision criteria. There is no interaction between the diagnostic and thesubsystem hardware. However, by entering the appropriate responses to thequeries provided, you will receive a list of possible hardware faults beginningwith the HP-FL PCA and running completely through to the last drive on thePBus. This is the section to choose if the other trouble tree sections do notidentify an error for you.Troubleshooting and Diagnostics 3-9