SCSI Miniport Driver Entries

The basic SCSI miniport driver entries in the Registry are found under subkeys in the following path:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services

The SCSI miniport driver recognizes the following optional value entries, which are used to fix problems such as device time-outs or controller detection errors but will reduce I/O performance. These value entries can be abbreviated. For example, a value entry of Disable will cause DisableSynchronousTransfers, DisableTaggedQueuing, DisableDisconnects, and DisableMultipleRequests to be set.

Note The system must be restarted before these options take effect.

DisableDisconnects REG_DWORD 0 or 1

Disables disconnects on the SCSI bus. It causes all requests to be executed sequentially.

Default: 1 (enabled)

DisableMultipleRequests REG_DWORD 0 or 1

Prevents the SCSI miniport driver from sending more than one request at a time per SCSI device.

Default: 1 (enabled)

DisableSynchronousTransfers REG_DWORD 0 or 1

Disables synchronous data transfers on the SCSI bus.

Default: 1 (enabled)

DisableTaggedQueuing REG_DWORD 0 or 1

Disables SCSI-II tagged command queuing on the host adapter.

Default: 1 (enabled)

DriverParameter Data type is specific to driver A string

A pointer to this data is passed to the SCSI miniport driver in a miniportFindAdapter routine. It is the fourth parameter, ArgumentString. A miniport driver uses this data to define the IRQ number for the SCSI host adapter, but other applications for the data are possible.

The data type for this value is defined by the specific SCSI miniport driver developer. If the data type is REG_SZ, the Unicode string is converted to an ANSI string before transferring it to the SCSI miniport driver.

The following driver currently uses the DriverParameter value entry for a setting that may affect performance:

Driver
Values
Meaning
Aha154x
BusOnTime=xx
xx is the bus on time in microseconds for the card. Valid values are 2–15. The default is 7. The value is usually adjusted downward when DMA transfers from the Adaptec card are interfering with other DMA transfers.

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Driver	Values	Meaning
Aha154x	BusOnTime=xx	xx is the bus on time in microseconds for the card. Valid values are 2–15. The default is 7. The value is usually adjusted downward when DMA transfers from the Adaptec card are interfering with other DMA transfers.