Avago Technologies LSI20160 - Manual (Page 114)

5-10 Windows 2000 Device Driver Installation
Copyright © 1993–2001 by LSI Logic Corporation. All rights reserved.
5.4 Performance Tuning for Windows 2000
Windows 2000 has registry entries that can be used to improve the
performance of SCSI I/O for certain configurations. The tunable
parameters are large transfer block size support and a guaranteed
number of concurrent I/Os for a particular SCSI bus.
Important: Registry files for the SYMC8XX.SYS , SYM_HI.SYS , and
SYM_895A.SYS and SYM_U3.SYS drivers begin with
SYMXXXXX.REG.
5.4.1 Large Block Size Support
The SYMC8XX.SYS , SYM_HI.SYS , SYM_895A.SYS , and SYM_U3.SYS drivers
can support up to a 1 Mbyte transfer size in Windows 2000, however the
default transfer size is limited to 64 Kbytes. To enable a larger transfer
size, an entry must be added to the registry, using the file
SYM_256K.REG .
This file sets a 256 Kbytes maximum, but it can be edited to set other
desired maximum transfer sizes.
Important: Be sure to read the information in the SYM_256K.REG data
file before editing it.
Choose one of two methods to add this registry setting:
1. Locate the SYM_256K.REG data file (supplied with the driver files)
using Windows Explorer and double click on the file.
or
2. Type at the command prompt:
REGEDIT SYM_256K.REG
This inserts an entry in the registry to enable 256 Kbytes block size
support.
Editing the SYM_256K.REG file can set any maximum block size between
64 Kbytes and 1 Mbyte (
−
8 Kbytes). The formula to calculate the proper
value for MaximumSGList is:
MaximumSGList = (Maximum Block Size)/4K +1
For 256 Kbytes: 256K/4K = 64 Kbytes, add 1 for 65 (decimal) or 0x41
(hexadecimal). The maximum value allowed for MaximumSGLIst is