Adaptec AHA-2940, 2940AU, 2940W, 2940U, 2940U Dual, 2940UW, 2940UW Dual, 2944W, 2944UW, 3940, 3940W, 3940U, 3940UW, 3940AU, 3940AUW, 3940AUWD, 3944AUWD HBAs

Preconfiguration Information

The Plug N Play SCAM Support option is not supported.

Known Problems and Limitations

• Some motherboards have problems supporting channel B with boards based on the Adaptec AIC-7895 chip, such as the AHA-2940U Dual, AHA-2940UW Dual, and the AHA-3940 series. The problem arises because the BIOS doesn't properly assign two interrupts for PCI interrupts INTA and INTB on the slot containing the AIC-7895 chip. This causes devices connected to channel B to fail, and messages about timeouts and resets on those devices to appear on the console.

  For example, this problem occurs on the Intel PR440FX (Providence) dual Pentium Pro motherboard, with BIOS revisions up to and including 1.00.08.DI0. For that motherboard, a workaround is to set the "Advanced/PCI IRQ Mapping" feature to "To ISA Legacy IRQs". A similar workaround may apply to other motherboards with problems supporting channel B.

  Another possible workaround is noted on Adaptec's Web site at http://www.adaptec.com/support/faqs/aha394x.html.

• To use the AHA-3940 or AHA-3940W adapters, the motherboard must have a BIOS that supports the DEC PCI-to-PCI Bridge chip on the host bus adapter.

• User-level programs have exhibited problems on some PCI systems with an Adaptec AHA-2940x card, including the following motherboard models:

  • PCI motherboards with a 60-MHz Pentium chip, with PCI chipset numbers S82433LX Z852 and S82434LX Z850. The part numbers of the Intel motherboards are AA616393-007 and AA615988-009.

  • PCI motherboards with a 90-MHz Pentium chip, with PCI chipset numbers S82433NX Z895, S82434NX Z895, and S82434NX Z896. The part number of the Intel motherboard is 541286-005. (Some Gateway 2000 systems use this motherboard.)

  • The AA-619772-002 motherboard with 82433LX Z852 and 82434LX Z882 chips causes random memory inconsistencies. Return the motherboard to the vendor for a replacement.

  If problems with user-level programs occur, use the BIOS setup to turn off write-back CPU caching (or all caching if there is no control over the caching algorithm).

• If the AHA-2940 SCSI adapter does not recognize the Quantum Empire 1080S HP 3323 SE or other SCSI disk drive, reduce the Synchronous Transfer rate on the Adaptec controller to 8 Mbps.

• The AHA-3940 has been certified by Adaptec to work on specific systems. Our testing has shown that the Solaris operating environment works properly in some of those systems and not in others. If you encounter problems running the Solaris operating environment on an Adaptec-approved system with the AHA-3940, contact your technical support provider.

Configuration Procedure

Using the Adaptec configuration utility:

• Configure each SCSI device to have a unique SCSI ID, and on the adapter's Advanced Configuration Options setup menu, set the Plug N Play SCAM Support option to Disabled.

• If there is more than one controller (or an embedded controller), try to use one IRQ per controller.

• Enable bus mastering for the slots with your host bus adapters, when the choice is given.

• For older disk drives, tape drives, and most CD-ROM devices, make sure the maximum SCSI data transfer speed is set to 5.0 Mbps.

• Enable support for disks larger than 1 Gbyte if applicable.