The Mole #13: Technical Answers from Inside Microsoft - Slow Network, Partition Size, Service Packs, IP Address

  • Article

July 19, 1999

Editors Note The questions and answers below are from the Inside Microsoft column that appears regularly on the TechNet Web site (https://www.microsoft.com/technet). To find out how to submit questions of your own, see the end of this article or go to https://www.microsoft.com/technet/community/columns/insider/default.mspx.

The TechNet Mole provides expert answers from deep within Microsoft to questions from IT professionals. This installment focuses on these issues:

  • Troubleshooting a Slow Network

  • All About Partition Size

  • Service Pack Compatibility

  • 3 NICs, One IP Address

On This Page

Throughput, Why So Slow?
Size, size, size. (That's partition size.)
Service Pack Blues
3 NICs, one IP address
Got Questions? Mail the Mole

Throughput, Why So Slow?

Dear Mole:

Having recently passed my MCP in NT Workstation, I am studying for my NT Server exams, and am looking into backup performance issues on our server. Our server is a 256MB P2-266 SCSI -based (Dual Adaptec 2940UW) with a Quantum DLT 4000 tape on a separate card to the UW HDD, latest drivers. NT 4 SP3.

Can you please point me to documentation of the registry settings for NTBackup? (HKey_Users.Default\Sotfware\Microsoft\ntbackup) I am particularly interested in the Backup Engine settings, especially the buffer settings. The default settings give us a backup speed of 16 MB/min., which is rather slow.

Quentin Stephens

Dear Quentin,

Spoken like a true MCP! Congratulations.

Now, you didn't specify, but I'll assume that the server that you describe (with the Quantum DLT) is acting as a backup server for other machines on the LAN. And you're right—16MB/min. is pretty slow. Don't rush to decide the problem is all NTBACKUP, though. In a network environment, several factors can impact throughput. The main areas that you should look at are SCSI-related issues, server performance, and the network itself.

First check the number of devices on the SCSI channel. With more SCSI devices on the SCSI channel, the overall throughput often decreases.

Proper SCSI cable length and resistance are also important. SCSI cables should have a minimum resistance of 90 ohms (as noted in the SCSI II spec), but many commercial SCSI cables fall well below this requirement. It's also important to maintain SCSI cable length requirements. Devices can be no closer than six inches apart, the maximum total cable length must be less than nine feet, and termination must occur within four inches of the end of the SCSI bus. Check for the correct termination. The internal SCSI terminator and the external termination on the backup device need to match—either both active or both passive. Mixing active and passive termination can significantly degrade performance.

Network issues: To determine if the network is the culprit, do a comparison backup – one from the host system (the one containing the tape drive) and one from a machine located somewhere on the network. Back up exactly the same data to make the test valid. If the difference is significant, then the network is most likely causing the slow-down.

If, after checking all this out, your throughput is still as speedy as a garden slug, then it really is time to take on the Registry. The Windows NT 4.0 Workstation Resource Kit is what you need. It's available on CD to TechNet subscribers or in book form from Microsoft Press (https://www.microsoft.com/mspress/) or bookstores, ISBN # 1-57231-343-9.

Size, size, size. (That's partition size.)

Mole:

I have a question that has yet to be answered. I am installing NT server 4.0 on an HP LC3 server. I would like to use the entire 9.1GB of disk space for my primary partition using NTFS, but I am limited to 1024 cylinders. How do I go about formatting the entire 9.1GB's of disk space (NTFS) at installation time?

agigley@U

Thank you, Agigley

Mole never in his wildest dreams imagined he would have the opportunity to write these words in his column: "Of course, size matters, but even more important is what you do with it." Know that this advice is given with nary a smirk, not one whisker aquiver. Mole is, of course, referring to hard drives.

Okay, let's do a short review. The Master Boot Record (MBR) on each hard disk contains the Partition Table, and the computer uses the partition table to determine how to access the disk. There is room in the partition table for four entries, called (not surprisingly) partitions. A partition is a portion of a hard disk that is set up to act like a separate physical hard disk. A partition must be completely contained on one physical hard disk. The MBR understands two types of partitions: primary and extended.

A primary partition is a portion of a physical hard disk marked as bootable by NT, is formatted with a particular file system, and is assigned a drive letter. With NT, there can be multiple partitions on a drive, of which one at a time can be marked "active", meaning that you can boot from it.

An extended partition is effectively a logical disk and can be subdivided into smaller logical drives. You can have only one extended partition per hard disk.

The "System Partition" is the partition that contains the hardware specific files used in loading and initializing the operating system. Only a primary partition can be used as a system partition. Windows NT actually requires that the system partition be a primary partition.

Then there's the Boot Partition. The boot partition is also used in starting the operating system and contains the operating system files needed by the OS. Both a primary partition and a logical drive in an extended partition can be used as a boot partition.

Got that? OK, review's over. The answer to your question is "No, you can't format the entire 9.1 gigabyte drive as the primary partition." Although Windows NT 4.0 can, in theory, support partitions of up to 16 exabytes in size using NTFS, the maximum size of the system partition is technically 7.8 GB.

Why is that? Blame it on Interrupt 13. During the boot process, the INT13 functions allow low-level code to read from and write to the drive. The INT 13 functions define 24 bits to describe a sector on the hard disk, and by way of a bunch of calculations using heads, cylinders, and sectors. The maximum number of bytes that can be addressed is 8,455,716,864, which comes out to is 7.8 GB. It's kind of like the Y2K thing—when the Int13 architecture was developed in the early 1980's, who dreamed anyone could possibly want or need multi-gig hard disks?

The INT13 functions are the only way the operating system can gain access to the drive and system partition until the operating system loads additional drivers that allow it to gain access to the drive without going through INT13. If you're getting the image of a snake chewing its own tail, you're onto something.

Some of Mole's friends with hot-swappable large disk arrays put Windows NT and any system utilities on the first drive and use the remaining drives for data. You lose a GB of disk, but they feel that the recoverability is worth it. Your call.

Here are some Knowledge Base articles for your reference:

  • 119497: Boot Partition Created During Setup Limited to 4 Gigabytes

  • 114841: Windows NT Boot Process and Hard Disk Constraints

Service Pack Blues

Dear Tech Mole:

My company is preparing to install NT 4.0, SP4 on our production servers. We are on hold because of the rumors of NT 4.0, SP3 and SP4 incompatibilities. Also, I have heard fellow NT administrators having problems with their production servers when they have some production servers with NT 4.0, SP3 installed and some production servers with NT 4.0, SP4 installed. When they installed NT 4.0, SP4 on some production servers, the production servers could not respond to production servers with NT 4.0, SP3 installed. Is this true?

JD McCreary, AT&T

Dear JD,

Not sure what you mean by "could not respond."

But here are two things Mole learned at the knee of Mother Mole. One: Maintain all your servers at the same Service Pack level. Two: Never ever apply a new service pack to a production environment until you've thoroughly tested it in a non-production setting. Just to be totally safe, Mole personally keeps his test LAN in a totally separate tunnel from the production LAN. Never the twain shall meet.

One thing to know is that you can't administer SP4 machines from SP3, e.g. using User Manager, Server Manager, etc. This comes from the SP4 readme file:

Running Windows NT Administrative Tools from Remote Server

In order to run administrative tools from a remote server, you must upgrade the remote server to Service Pack 4. If you attempt to run administrative tools from a remote machine that hasn't also been upgraded to Service Pack 4, it will fail to load or won't function properly.

That sort of says it all, huh? There have also been reports of logon problems with SP4 on the client and SP3 on the server, but nothing has been substantiated. Here's one last resource regarding clients running SP3 and the server running SP4:

  • 196289: SP3 Clients Cannot Change Passwords - Error C00000BE

Upgrade everything at once. Test first. May the force be with you.

3 NICs, one IP address

Greetings:

This is what we want to do:

Compaq ProLiant 5000, 3 3com EtherLink XLs. We want to bind these NICs to the same IP address to provide IP Load sharing. Can it be done? We are being told yes, but no help on how. If so, how???

SSgt. Kevin Fox, Hill AFB, Utah

Kevin,

It sounds like you want to have three network cards with the same IP address, all installed on the one ProLiant. If this is the case, then the answer is No—you can't bind the same IP address to multiple network cards. Having the NICs in one computer vs. one in each of three computers doesn't matter—you still can't do it.

If you have a multi-homed computer (with different IP addresses for each NIC), the Windows NT implementation of TCP/IP will help to distribute the number of connections, or sessions among the adapters according to a randomizing algorithm. Perfect load balancing, meaning even network bandwidth on all NICs, just isn't possible. However, Windows NT is able to distribute connections from clients across multiple NICs. This helps to spread out the network traffic.

Here's a good Knowledge Base article that discusses load balancing:

  • 131736: TCP/IP—Load Balancing vs. Distributed Network Sessions

If your need for load balancing is for something like a high traffic web server, then there may be a reasonable solution in Windows NT Load Balancing Service (WLBS). Check out these articles:

Got Questions? Mail the Mole

Communicate with Mole at [closed account]. Send him your toughest questions. And if you think you have a better answer than Mole's, or a different one, send that along, as well. Please include the following:

  • Your name

  • Your title

  • Your company

  • Your e-mail address

  • Your question/solution/compliment

Credits

Mole thanks Chuck Anderson, Lon Collins, Michael Conrad and Lester Russell.

We at Microsoft Corporation hope that the information in this work is valuable to you. Your use of the information contained in this work, however, is at your sole risk. All information in this work is provided "as -is", without any warranty, whether express or implied, of its accuracy, completeness, fitness for a particular purpose, title or non-infringement, and none of the third-party products or information mentioned in the work are authored, recommended, supported or guaranteed by Microsoft Corporation. Microsoft Corporation shall not be liable for any damages you may sustain by using this information, whether direct, indirect, special, incidental or consequential, even if it has been advised of the possibility of such damages. All prices for products mentioned in this document are subject to change without notice.