HP LeftHand SAN Solutions Support Document - Application Notes - Best Practices for Enabling Microsoft Windows with SAN/iQ®
Table Of Contents
- Application Notes Best Practices for Enabling Microsoft Windows with SANiQ
- Contents
- 1 Chapter: Enabling LeftHand SAN volumes with the Microsoft™ iSCSI 2.0x Initiator
- 2 Chapter: Finding the iSCSI Initiator Version
- 3 Chapter: LeftHand Networks and Microsoft™ MPIO Support
- 4 Chapter: Expanding a Windows Volume on the SAN
- 5 Chapter: Shrinking a Windows Volume on the SAN
- 6 Chapter: Setting the Windows Disk Partition Offset for Optimal Performance
- 7 Chapter: Ensure That Application Resources on iSCSI Volumes Come Online After a Server Reboot
- 8 Chapter: Microsoft™ iSCSI Initiator Session Timeout Setting
- 9 Chapter: Measuring Performance in a Windows Environment
- Overview
- Using Windows Performance Monitor to Measure SAN Performance
- Setting up Windows Performance Monitor
- Saving a Performance Monitor Log for Analysis
- Monitoring More Than One Server Simultaneously
- Scheduling Performance Data Collection
- Using IOMeter as a SAN Benchmark Tool
- Configuring the ISCSI Volume
- Configuring IOMeter
- Configuring IOMeter Access Specification for each Test
- Running the Test
- Interpreting Results
- Access Specifications to Run
- 10 Chapter: Frequently Asked Questions
60
Note: Starting with SAN/iQ version 7.0, the iSCSI timeouts on the SAN
have been reduced such that changing the MaxRequestHoldTime is
technically no longer necessary. However, in order to compensate for
iSCSI issues outside of SAN control, such as network disturbances,
etc., LeftHand still recommends changing the MaxRequestHoldTime
value to 600 seconds.
Note: Any time the iSCSI initiator is reinstalled or upgraded, the
MaxRequestHoldTime value may revert to its default value of 60
seconds. Always reconfirm this setting after reinstalling or upgrading
the initiator.
The timeout for the Microsoft™ iSCSI Initiator is controlled via a Microsoft™
iSCSI Registry entry named MaxRequestHoldTime.
Note: The MaxRequestHoldTime value should be modified on every
Windows system with an iSCSI volume. This recommendation also
applies to cluster nodes using iSCSI resources in Microsoft™ Cluster
Service (MSCS).
Caution: LeftHand Networks does not recommend setting
MaxRequestHoldTime to FFFFFFFF (i.e., infinite). The downside of using the
infinite setting for MaxRequestHoldTime is that the server’s cache memory
may become full with pending iSCSI data that is waiting to be written to the
SAN, which can result in a degradation of server performance – and can lead
to a complete lock up of the system. For that reason, LeftHand Networks
recommends setting MaxRequestHoldTime to 600 seconds (10 minutes).
Procedure
The following procedure sets the MaxRequestHoldTime value to 10
minutes:Caution: Take standard precautions when editing the registry. If you
are not comfortable with this process, consider making a backup copy of the
registry before starting. For more information on backing up, editing and
restoring the registry, please refer to the following Microsoft™ Knowledge
Base article:
• Description of the Microsoft™ Windows Registry
http://support.microsoft.com/default.aspx?scid=kb;en-us;256986
1 To start the registry editor in Windows, click on Start and select Run from
the menu.
2 Type regedit in the available Open: field, and click on OK.