NT detects only eight logical units on SCSI device

  • Section(s): TroubleShooting
  • Published on Apr 20, 2004.
  • Last Modified on Apr 20, 2004.
  • Last Modified by Wayne Maples.
  • Rating: Not Rated
Modern SCSI controllers support many logical units (LUs). By default NT will only detect the first eight LUs on a scsi controller unless the parameter value DevicenLargeLuns has been set for the driver of the scsi card where n is the scsi bus number. For the Adapter2940 which Dell widely uses:

Hive: HKEY_LOCAL_MACHINE
Key: SYSTEM\CurrentControlSet\Services\aic78xx\Parameters
Name: Device0LargeLuns bus 0
Name: Device1LargeLuns bus 1
Type: REG_DWORD
Value: 1 enable

After setting DeviceLargeLuns for the appropriate bus, the SCSI will detect whatever the number of LUs supported.

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