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1997-06-02
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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.