Avago Technologies LSI SAS 3041E-R - Manual (Page 31)

Installing the Windows XP Driver 2-9
Version 1.3 Copyright © 2001, 2002, 2007 by LSI Logic Corporation. All rights reserved.
2.2.6.2 Maximum Number of Concurrent I/Os (Guaranteed)
Windows XP guarantees a maximum of 32 concurrently active I/Os on a
particular SCSI bus. Due to the method of memory allocation, the actual
limit of concurrent I/Os can vary between different drivers or versions of
drivers. This can have a significant impact on performance benchmarking
between different driver versions or adapter vendors. In effect, one
adapter may be able to support 70 or 80 outstanding I/Os, while another
adapter could support only 32 outstanding I/Os. This can also affect
systems with high performance storage subsystems, such as disk arrays.
To enable better performance, the driver installation process adds a
registry entry to support 255 concurrent I/Os. If you want a different
maximum value, you can use the
mpi100io.reg data file to add a
registry entry that sets the maximum number of concurrent I/Os. There
are two ways to add this registry setting:
•
FInd the mpi100io.reg data file using Windows Explorer, double-
click on the file name, and edit it to change the maximum concurrent
I/Os to some other number. (This file is included with the driver files.)
•
Type the following at the command prompt:
regedit mpi100io.reg
This command inserts an entry in the registry to guarantee a
maximum of 100 concurrent I/Os per adapter.
Be sure to read the information in the mpi100io.reg data file before
editing it. If you set the number of concurrent I/Os to a high number, large
amounts of non-paged pool memory (a critical NT resource) will be used
and system performance can be degraded.
To reset the guaranteed number of concurrent I/Os to the Windows XP
default of 32, follow the instructions above but use
mpidefio.reg as the
data file.
You must reboot the system for the new registry settings to take effect.
2.2.7 Hibernation Support
The LSI Fusion-MPT storage adapters and the SYMMPI.SYS driver are
high-performance storage solutions. This performance level requires
more resources than typical storage adapters. Windows XP supports this
resource level adequately during normal operations. However, due to