Set Sail For Uncharted NT Performance

I enjoyed Sean Daily’s September article. However, I’d like to add a couple of comments. Mr. Daily’s article was unclear on two points.

First, he recommends spreading the paging file across a stripe set. Although this method will generally increase performance, you do not want to put the paging file across a stripe set with parity. There is no reason to use parity for a paging file, and doing so will significantly reduce performance during write operations.

Second, the memory configurations Mr. Daily discusses leads him right back to, “In most cases, you’ll find that the Balance settings give the best overall performance.” Mr. Daily points out what’s underneath the user interface (Registry keys, LargeSystemCache) but doesn’t mention some simple guidelines for optimizing memory settings in NT.

Each setting corresponds to specific uses. If you have fewer than 10 users, you’ll find that the Minimize Memory Used setting will increase throughput. If you’ve got a larger number of users, the Balance setting works best. If you are using the server to host an application (such as an Access database) that requires a lot of file sharing, your performance will improve if you use Maximize Throughput for File Sharing. Finally, if you’re using the NT server as a SQL server or other BackOffice-type application (client/server), you’ll want to optimize performance by using Maximize Throughput for Network Applications.

By default, NT servers are configured to give preference to the file system cache over the working sets of processes. However, occasionally you will want to change to Maximize Throughput for Network Applications, because you will encounter processing delays from writing pageable code to disk (e.g., when using IIS). I look forward to future articles on performance tuning.

--Susan Snedaker

Thanks for your letter. Your clarifications are on the money—I agree that you should never spread paging files across stripe sets with parity (RAID 5) volumes. This action actually degrades performance because of parity overhead and the lower write performance of RAID 5 volumes.

I also agree that I need to clarify the functions and intended uses for each of the Server service configuration options. Microsoft intended each of these options for a particular situation based on the number of users and intended role of the server. Although the focus of my article was to inform readers of what goes on behind the scenes (in the Registry), understanding the basics is important.

I also have a clarification to your comment about the Maximize Throughput for Network Applications setting. Although you state that this setting is best for SQL Server, this recommendation is not always correct. SQL Server performs its own internal memory management (rather than relying on NT’s management scheme), and as a result doesn’t always work best with this setting. Often, the Balance or Maximize Throughput for File Sharing options will yield equal if not better performance on SQL Server systems. In any case, it’s always a good idea to do liberal benchmarking to decide which is best in a particular situation.

--Sean Daily

Thank you for Sean Daily’s September article, “Set Sail for Uncharted NT Performance.” Basically, I run one program, AutoCAD, with an occasional trip to a word processor for long text notes to import into AutoCAD.
I learned a long time ago (version 1.1) that if you properly set up and configure AutoCAD, it is virtually failsafe, not prone to the dreaded fatal error. However, few people would listen to me or even bother to look at the installation manual. Now, AutoCAD comes without all the manuals—you must buy them. Thank you for this article!

--Ted Harris

After reading Sean Daily’s September 1997 article, “Set Sail for Uncharted NT Performance,” I have a couple of questions: First, why does shutting down NT take so long? Can I speed up the startup/shutdown process, other than by disabling services? Second, I get a strange delay of about 10 to 15 seconds at the command prompt when I run most anything (e.g., EDIT). After executing a program once, the next time I run that program it pops up right away as I would expect. Obviously some caching is happening. I don’t understand why these various DOS-based programs take so long to execute initially.

—Bryan Keadle



NT 4.0 seems to take a lot longer than NT 3.51 to shut down, especially on NT server computers. Although you can’t do much to speed the startup process other than disabling services or obtaining faster hardware, you can do things to reduce the length of time the shutdown process takes.
The Server and Spooler services commonly cause the exaggerated shutdown delays. To speed up the shutdown procedure significantly, you can shut down these services manually (e.g., via the Services Control Panel or via the NET STOP command line method) before executing the Shutdown process. Other potential candidates for manual pre-shutdown include Windows Internet Naming Service (WINS), Dynamic Host Configuration Protocol (DHCP), Internet Information Server (IIS–all services), and Domain Name System (DNS).
I’ve seen the process take one-fourth as long as it takes if you stop no services ahead of time. With the command-line method and placing the respective NET STOP commands into a batch file, you can consolidate this process into one command (or icon) that you can execute before issuing the shutdown command. For example, you can enter the following lines:



NET STOP “Spooler”

NET STOP “Server” /Y



(The /Y switch is necessary because the system will prompt you if dependent services also need to be shut down before the Server service. When you issue /Y, the dependent-
service shutdowns will automatically occur.)
Microsoft Exchange Server (any version) also slows the NT Server shutdown process. To significantly reduce the shutdown time of an Exchange Server, manually shutdown the Exchange-related services before you issue the Shutdown command. Although you can individually select each Exchange service in the Services Control Panel and shut down each, an easier method uses the following two simple lines:



NET STOP “Microsoft Exchange System Attendant” /Y

NET STOP “Microsoft Exchange System Attendant” /Y



The System Attendant service, shutdown with the /Y switch, will automatically shut down all the Exchange-related services. The second line ensures that the System Attendant service shuts down after the other services shut down in the first step. (In Exchange 4.0, the first command doesn’t shut down the System Attendant service, just the other, dependent services). Some Exchange 4.0 installations might require three iterations of the command to stop all Exchange-related services.
Regarding your second question, I don’t know what’s causing the delay, but I can let you in on a secret that affects the initial execution of 16-bit Windows applications under NT. The first time a 16-bit DOS or Windows application launches, NT starts a special Virtual DOS Machine (VDM—with the executable name ntvdm.exe) that contains the Win16 on Win32 (WOW) subsystem required to provide Win16 application support under NT. Even after all 16-bit Windows applications are closed, NT keeps the VDM and WOW subsystem environment active in memory, and doesn’t remove them until you restart the system or stop the process manually (e.g., via the Processes tab of Task Manager). If you run 16-bit applications under NT and want the first Win16 application to load faster, consider placing a shortcut to wowexec.exe in your Startup group. This method will preload the WOW subsystem and make it instantly available when you later execute your first Win16 application. (It will also waste some system resources if you don’t end up using any Win16 applications.) I discuss these and other Win16 subsystem-related optimizations in “Optimizing NT’s WOW Subsystem,” page 151.

--Sean Daily

In the December 1997 issue, Susan Snedaker wrote concerning Sean Daily’s optimizing NT performance article. Susan says you have no reason to put NT paging files on a RAID protected stripe, and Sean agrees.
Assuming system uptime is critical, having the paging files on a RAID protected stripe is important. If a drive with the paging file fails, the system will go down instantly. RAID 5 is probably not the performance solution; RAID 1 or a mirrored stripeset is preferable. In a mission critical environment, RAID protection of the paging file is a necessity, not a luxury.

--Nik Simpson

After reading Sean Daily’s NT Performance article, I tried to implement regback.exe from the Microsoft Windows NT Server Resource Kit. I continually got an error that said the backup failed and gave an address of 0x00000003. (I have Administrator privileges.) Great article. Keep up the great work.

--Rus Smith



I find that REGBACK fails to back up files into the same directory where a previous REGBACK-created backup exists. Be sure that no existing Registry backup exists in the target directory. Get the latest updated version of REGBACK from the Microsoft Windows NT Server 4.0 Resource Kit, Supplement 2. Your problem might stem from an inability of the original version to back up the Registry based on something in your NT environment.

--Sean Daily