The Mole #29: Technical Answers from Inside Microsoft - Disk Mirror, DHCP, Service Packs, Windows 2000 Names

February 28, 2000

Editors Note The questions and answers below are from the Inside Microsoft column that appears regularly on the TechNet Web site at the following location: https://www.microsoft.com/technet/community/columns/insider/default.mspx. 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:

• Of failed drives and broken mirrors

• No automatic renewal of DHCP lease

• Mole's Service Pack Diatribe

• W2K Hot Tip: How to Find New Names for Old Functions

• BackTalk: A Q, an A

On This Page

Of failed drives and broken mirrors

No automatic renewal of DHCP lease

And now, Mole's Service Pack Diatribe....

W2K Hot Tip: How to Find New Names for Old Functions

BACKTALK

Credits

Of failed drives and broken mirrors

Mole,

Disk mirroring for Windows NT may be great, but what if the mirror is broken somehow? How can a program (VB in particular) find out the status of a mirror? If I could find that out, then I can automate whatever response is needed. Windisk has to be using some API, do you know what it is? Can you help me out?

Paul Enright, Braums Ice Cream Inc.

Hey Paul,

This is going to be a loooooooong answer. Your question is so short, Mole's not 100% sure what you want to do. Since he's not psychic, he can at least be thorough, right? So here goes.

As far as Mole knows, a mirror never breaks, it's deliberately broken, either because one of the mirrored drives in the set fails, or because you decide you don't want to mirror your drives anymore—you'd rather have the disk space than the safety net, let's say.

If you want to know when there's a problem with a fault tolerant set, you can set up administrative alerts, which will advise you by various means (pager, email, etc.) when a particular event has occurred on specific systems.

Normally, we would just go into Performance Monitor and configure what alerts we want to track. The thing is, not all Windows NT events that we may be interested in are accessible from Performance Monitor GUI. That's why the utility logevent.exe was created.

Logevent.exe is a command line utility and can be used to log an event ID provided by the user into the event log. This allows the user to log errors and informational data from batch files, login scripts, and Performance Monitor. The event log can then be viewed and manipulated with the standard tools used for dealing with event logs.

Where to get LOGEVENT?

The Logevent utility is included in the Windows NT 4.0 Resource Kit Support Tools. Available on TechNet on the CD titled, Windows NT 4.0 Resource Kit Utilities: September 1999, the Windows NT 4.0 Resource Kit Support Tools are a set of tools that help you support, administer, and troubleshoot the NT Server 4.0 and NT Workstation 4.0 platforms. Details about usage are included in the Support Tools help file.

Mole has also dug up the most appropriate Event IDs that you would be interested in. Here they are:

Lastly, some information on how to how to deal with things when they go south:

• Troubleshooting Fault Tolerance (FT) in MS Windows NT : A section at the end lists articles in the Microsoft Knowledge Base that treat in more detail the topics covered procedurally in this article.

Broken mirrors, part deux, addresses the possibility you're actually looking to automate a fix after a drive has failed, in which case, Mole has bad news. Even a program as doughty as Visual Basic isn't going to be able to cure what ails you. They still haven't devised a program to make little virtual hands grab a Phillips screwdriver and swap the bad disk (or controller) for a nice new one. Mole is told this is on the short list of enhancements you can expect to find in VB 18.0, but until then, Paul, you're going to have to get your own hands dirty.

So, assuming we're talking failed drive here, Mole has many many questions. For starters, which drive failed? How up to date are your backups? Have the backups been tested recently? Does the failed drive contain the system partition? Do you have an up-to-the-minute emergency boot disk? Will you need to edit the boot.ini file?

There's a fundamental problem occurring when a mirrored set fails, of the kind Mole believes deserves and requires individual attention. Rather than trying to automate a fix, Mole recommends leaving your cozy burrow to investigate the problem thoroughly before deciding how to address it. If your solution means replacing a controller card or a disk, make it easy on yourself by using the exact same model you had before.

You don't say whether mirror failure is an endemic problem in your systems. If it is, your first job should be to figure out why they're failing. Mole's provided a detailed reading list to help you out. You'll find it at the end of this note.

Meanwhile, if there's still stuff you want to automate, you can find more info on Windows and NT APIs over on the Microsoft Developers Network Web site (https://msdn.microsoft.com). That's what they do best.

Ready to dig in? Here's your assigned reading, Paul.

• Preparing for and Performing Recovery

• 119467: Creating a Boot Disk for an NTFS or FAT Partition

• 113977: Booting From Mirror After Primary Partition Is Lost

• 114779: Overview of Disk Mirroring (RAID Level 1) in Windows NT

• Q96735: Hardware/Software Requirements for Fault Tolerance

• 114872: Restoring Disk Configuration Information

• 141702: How to Recover Mirroring Windows NT Using IDE Devices

• 172912: Windows NT May Appear to Hang When a Mirrored IDE Drive Fails

• 102873: BOOT.INI and ARC Path Naming Convention and Usage

• 161563: How Windows NT Handles Drive Translation

• 148425: Duplexed Mirror Fails with Insufficient Space

Mole closes with a bit of wisdom from the Moleish Mater. "Everything should be made as simple as possible, but not simpler." Got that?

M. le Fur

No automatic renewal of DHCP lease

Mole,

So here's the question of the century…

I have a network with approximately 20 clients running Win 95 SR2 and two NT Servers. One of the Windows NT servers, the PDC, is acting as the DHCP server for the network. For 90% of the machines, it works great, but for about 3-4 of the machines, if the DHCP lease expires when the computer is off, it won't automatically renew when you turn it back on.

If you leave the machine running for a while, it will renew, or if you go into "winipcfg" and hit the "Renew" button, it will renew.

All of the computers are configured the same as near as I can tell. Any thoughts?

David Buerer

David,

Jeez, man. Mole can't wait to see what the remaining 36,400 days of the century, give or take, are going to bring into his mailbox! Anyhow, he hopes this is the toughest issue you have to tackle before your lease expires.

What makes your problem knotty (naughty?) is that only some of the clients are exhibiting the weird behavior. Let's be good problem solvers and take a look at what we know:

If a scope is removed in DHCP Manager and another scope is defined, Microsoft-based DHCP clients will not automatically renew their lease to conform to the new scope. More information in Knowledge Base article **154488:**Automatically Reset DHCP Leases for Win95/WinNT/WFWG Clients. That's one possibility.

Now, consider the possibility that your second server might also be configured as a DHCP server. When your Dynamic Host Configuration Protocol (DHCP) clients attempt to lease or renew IP lease information, they may receive the following error message: "No DHCP server available."

What causes this is that your DHCP server is configured to be a DHCP Relay Agent in addition to a DHCP server. This causes the DHCP server to forward any DHCP Discover packets to another server without responding directly to the DHCP client. Confusion ensues.

If this sounds like what you're seeing, then you need to remove the DHCP Relay Agent configuration on your DHCP server:

1. Click Start, point to Settings, and click Control Panel.

2. Double-click Network, click the Protocols tab, and double-click TCP/IP Protocol.

3. Click the DHCP Relay tab.

4. Remove all IP addresses listed in the DHCP Servers list by clicking each address and then clicking Remove.

And now, Mole's Service Pack Diatribe....

You neglected to tell Mole a couple of very important things when you submitted your question—namely, the Windows NT version and Service Pack you're running. At the risk of overstating the obvious: THE MORE INFO YOU GIVE MOLE, THE BETTER HIS ANSWER IS GOING TO BE.

The Obvious, continued—SERVICE PACKS FIX BUGS. It may be that the problem you're experiencing has been addressed in an SP more recent than the one you have, in which case your problem's pretty much a no-brainer. As an example, here are just three DHCP problems that were fixed in Windows NT 4.0 Service Pack 4:

• 177357: DHCP Client Does Not Immediately Renew Address

• 163055: DHCP Client May Fail With WinNT 4.0 SP2 Multi-netted DHCP Server

• 194424: DHCP Server May Fail to Record Lease

These sample articles were taken from the following Knowledge Base article:

• 184693: DNS/DHCP/WINS Release Notes for Windows NT 4.0 SP4 Update

And how did Mole unearth these tasty bits of arcana? With a pointed query (often as useful as a good shovel for unearthing answers)—DHCP SP fixes. Please, oh please, try this at home.

W2K Hot Tip: How to Find New Names for Old Functions

This column's prize (a juicy worm, what else?) for Shortest Question with No Missing Parts goes to IT Pro Douglas Cox, who asks, ever so succinctly, "Where is User Manager for Domains in Windows 2000?"

Doug, Mole's glad you asked him that.

Many components from Windows NT 4.0 have changed names or locations in Windows 2000. To help IT Pros like Douglas and everyone else find their way around, the Windows 2000 developers included a great little feature in Win2000. If you click the Start button, then Help, you are presented with the Windows Help screen. On the left are the usual Contents, Index, Search, etc. The cool new thing is on the right half of the Help window--a link called "New ways to do familiar tasks".

Click that and you can go to the section that you knew in Windows NT 4.0—say "U" for User Manager for Domains. You will be instantly transported to the "U" section and there, right before "V" you will see User Manager for Domains. Click that, and it displays a nice table that lists all the common tasks you used to do in User Manager for Domains and tells you how it's done in Windows 2000. There's even hyper links that deliver you exactly where you need to be. (Even a cynical old Mole might admit to being a little bit impressed.....)

And to answer Doug's delightfully direct question in kind, most of the functionality of User Manager for Domains is now available under Active Directory Users and Computers. To get there from here, select Start, Programs, Administrator Tools, and then Active DirectoryÔ Users and Computers. You're there, man.

Mole

BACKTALK

Mole,

On the "40 or 128-Bit—Which Version Do I Have?" question – you can also get this information in Internet Explorer: select Help > About.

And a question of my own: Where can I find a detailed procedure for promoting my BDC to a PDC?

TIA, Eyal Mokady

Thanks for the tip, Eyal.

Now for your question. There's not much detail to the procedure for promoting a BDC. All you have to do is start Server Manager, select the BDC to be promoted, and choose "Promote to Primary Domain Controller" command on the Computer menu. Don't you wish everything was that simple?

Mole

Credits

Sing a song of Lon.

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