IBM RS6000 Service Guide - Page 263

Appendix A. SSA Problem Determination Procedures Problem determination procedures are provided by power-on self-tests (POSTs), service request numbers (SRNs), and maintenance analysis procedures (MAPs). Some of these procedures use the using system service aids that are described in "SSA Service Aids" on page 3-64. Disk Drive Module Power-On Self-Tests (POSTs) Attention: Disk drive modules are fragile. Handle them with care. Follow all ESD-sensitive parts procedures when handling disk drive modules. For ESD information, see "Handling Static-Sensitive Devices" on page 6-2. The disk drive module POSTs start each time the module is switched on or when a Send Diagnostic command is received from the SSA adapter. They check whether the disk drive module is working correctly. The POSTs also help verify a repair after a FRU has been exchanged. There are two power-on self-tests: POST-1 and POST-2. POST-1 runs immediately after the 'power-on reset' line goes inactive, and before the disk drive module motor starts. POST-1 includes tests of the: Microprocessor ROM Safety circuits If POST-1 completes successfully, POST-2 is enabled. If POST-1 fails, the disk drive module check light stays on, and the disk drive module is not configured into the SSA network. POST-2 runs after the disk drive module motor has started. POST-2 includes tests of: Motor control Servo control Read and write on the diagnostic cylinder (repeated for all heads) Error checking and correction (ECC) If POST-2 completes successfully, the disk drive module is ready for use by the using system. Appendix A. SSA Problem Determination Procedures A-1