There is a good possibility that Adaptec doesn't have a driver for Solaris 7 that support the 2944, you could inquire via email.
Is the DLT4000 a Single-Ended SCSI device? Remmember the 2944 board is a DIFF controller. So there isn't compatibility between the above two devices.
Here are some number for supported Sun controllers.
Option X5010A P/N 375-0097 Single channel Single Ended
Ultra/Wide SCSI PCI
Option X6541A P/N 375-0006 Dual Differential Ultra/Wide
Both options fully support Soalri 2.5 thru Solaris 9.
By the way if you would like to boot your system to 32 bits and try the Adaptec driver you could give it a try.
Here are examples on how to boot 64 or 32 bits O/S.
Q5. How do I configure the system to boot a 64-bit kernel?
If the system's hardware and software support 64-bit, the system will by default boot the 64-bit kernel. The OBP boot-file variable will by default be set to a null value. boot-file may also be set to "kernel/sparcv9/unix". Check the boot-file variable by using either the Solaris eeprom command or the OBP setenv command.
eeprom: Login as root and use the eeprom command:
# /usr/sbin/eeprom | grep boot-file
If the output from the eeprom command is either:
boot-file: data not available
or
boot-file=kernel/sparcv9/unix
then the system is configured to boot the 64-bit kernel. The boot-file does not have to be set to kernel/sparcv9/unix. A null value works.
If the output from the eeprom command came back as
boot-file=kernel/unix
then the system is configured to boot a 32-bit kernel. Set the boot-file variable to either null or "kernel/sparcv9/unix"
/usr/sbin/eeprom boot-file=""
or
/usr/sbin/eeprom boot-file="kernel/sparcv9/unix"
setenv: From the system's OBP OK> prompt, use the printenv command to check the boot-file variable and if necessary use the setenv or set-default command to set the 64-bit kernel:
OK> printenv boot-file
OK> setenv boot-file kernel/sparcv9/unix
or
OK> set-default boot-file
Q6. How do I configure the system to boot a 32-bit kernel?
If the Ultra machine meets the hardware and software requirements for 64-bit boot, the boot-file OBP variable must be set to kernel/unix. If not, then the machine will boot 64-bit. The boot-file variable can be set by either the Solaris eeprom command or the OBP setenv command.
eeprom: Login as root and use the eeprom command to set the boot-file parameter to the 32-bit kernel:
# /usr/sbin/eeprom boot-file="kernel/unix"
The next system reboot will boot the 32-bit kernel.
setenv: From the system's OBP OK> prompt, use the setenv command to set the boot-file parameter to the 32-bit kernel:
OK> setenv boot-file kernel/unix
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IF YOU HAVE APPS RUNNING THAT REQUIRES 64 BITS THEN DON'T BOOT WITH 32 BIT O/S. OTHERWISE YOU CAN FROM 64 TO 32 AND BACK TO 64 FOR TESTING.