OSIN68AD - 6886-PCH SYSTEMS EXHIBIT RANDOM LOCK UPS IN A SERVER CONFIGURATION, WITH REVISION "B" ADAPTEC 2940 SCSI ADAPTER 12/02/96 ======================================================================= 6886-PCH Systems Exhibit Random Lock Ups in a Server Configuration, with Revision "B" Adaptec 2940 SCSI Adapter ======================================================================= Please Read Entire Document for Full Explanation of Procedures -------------------------------------------------------------- DESCRIPTION IBM Model 6886-PCH systems, configured as Servers and using the Revision "B" Adaptec 2940 SCSI adapter (AIC7870B), lock up, from once a day to as often as every 20 minutes. When the failure occurs, the hard disk access light stays on and the system must be powered off to recover. Following is a report from Adaptec describing their findings: "Upon investigating problem reports by early AIC7870B (revision B) users, we have discovered and identified through rigorous compatibility testing two potential data loss problems that can occur in the AIC-7870B. These problems arise from trying to synchronize between the PCI and AIC-7870B clocks. The problems are dependent on the coincidental occurrence of relatively rare events in sequence. They are difficult to reproduce and see, since they are highly speed and system dependent. The problems were not found earlier because most systems being used for debugging are built around the slower Intel Saturn-1 chipsets. Adaptec has identified the problems and is currently implementing a solution in silicon for it." "The symptom of this problem is an 8 byte drop when writing to disk and an 8 byte repeat when reading from disk. Investigation found that during data burst transfers on the PCI bus, the possibility exists for a glitch to be generated on a synchronization clock to an internal 8 byte holding FIFO causing the 8 byte drop or repeat." The part numbers of the affected part are: IBM MFG. P/N 06H4579 and FRU P/N 06H5250. RESOLUTION If you have an Adaptec 2940 REV. "B" SCSI adapter (P/N 06H4579), in a Model 6875, 6876, 6885, or 6886 (MACH) desktop system, and are experiencing lockups, contact the hardware vendor for a replacement adapter. The REV."B" adapter can be identified by looking for P/N 06H4579, on the component side of the adapter. The FRU P/N is 06H5250. Not all of the Adaptec 2940 adapters exhibit the problem. Adaptec has commented that due to process fluctuations on their 7870 chip fabrication line, some of the controllers may be within specification, others may not. There was no way to zero in on which lot ranges of components would or would not have had the problem. Adaptec has corrected the AIC-7870 clock issue, by implementing a silicon fix in the controller chip. This chip is used on Revision "C" 2940 SCSI adapters, with version 1.11 BIOS. The REV."C" adapter is under the following IBM P/N's: P/N: 06H9607 FRU P/N: 06H9610 Any Commercial Desktop systems released after the (MACH) models mentioned above are not exposed to the REV "B" 2940 problem. All of the later released models use a 2940 adapter that has been designed with the corrected AIC-7870 controller chip. Note: These later models will not function properly if the REV "C" adapter, with version 1.11 BIOS, is installed. Adaptec has released new levels of the 2940 SCSI adapter, with unique BIOS, that must be used in these follow on models. ______________________________________________________________________ IBM disclaims all warranties, whether express or implied, including without limitation, warranties of fitness and merchantability with respect to the information in this document. By furnishing this document, IBM grants no licenses to any related patents or copyrights. Copyright (c) 1994, 1995 IBM Corporation. Any trademarks and product or brand names referenced in this document are the property of their respective owners. Consult your product manuals for complete trademark information.