NT Replication feature

Ghost · Jun 2, 1999

We run a web server using IIS (on a single drive) and will be installing two new larger drives into the server. We would like to use the NT replication feature. 
 
We are making the change for additional redundancy in our system. The goal being that if one of the drives goes down, we can still run while the other is being swapped out. 
 
We are really more programmers than NT or hardware proficient. Can anyone offer any advice to us that has set up replication on NT. And, if you've done this running an IIS web server app it would be even better. Any advice from someone who has set this up (regardless of how basic) would be greatly appreciated. 
 
Thanks for the help. 
 
Ghost

SRG · Jun 2, 1999

The NT mirriring feature is probably not the best idea. If you can afford a RAID controller and mirror the drives that way you might be better off. If you still want to use NT you will have to use something like Ghost to copy the information from the old drive to the new one. Then perhaps something like partition magic to rezize the partitions if you need to. Then boot NT from the new larger drive. Then use the disk administrator to create a mirror set from two identical formated partitions. You will want to make an NT emergency repair disk and a drive failure boot disk the the ACR path in the boot.ini altered to point at the second drive. If you need more detail let me know.

Ghost · Jun 2, 1999

Thanks. Unfortunately RAID is not an option due to cost right now. Your answer is pretty much in line with what we were thinking we needed to do, and the heads-up on the emergency repair disk is greatly appreciated. 
 
However, we were wondering if anyone currently runs a NT Replication set-up and has actually had a disk go out. Does it actually keep a system running while the repair is made to the bad disk? Does it actually do what it says it will do? 
 
Not to be too cynical on this whole Replication thing, but we've been bitten too many times with promises, and our web server is mission critical (24x7 and getting busier all the time) 
 
Thanks, 
 
Ghost

SRG · Jun 2, 1999

It does keep the system running with one failed drive. 
 
read this 
 
 
PSS ID Number: Q114779 
Article last modified on 07-01-1998 
 
3.1 3.5 3.51 4.0 
 
WINDOWS 
 
 
====================================================================== 
---------------------------------------------------------------------- 
The information in this article applies to: 
 
- Microsoft Windows NT Advanced Server version 3.1 
- Microsoft Windows NT Server versions 3.5 and 3.51 
- Microsoft Windows NT Server versions 4.0 
 
---------------------------------------------------------------------- 
 
This article provides an overview of disk mirroring (RAID Level 1) under 
Windows NT. 
 
In disk mirroring, partitions on two drives store identical information so 
that one is the mirror of the other. All data written to the partition on 
the primary disk is also written to the mirror, or secondary, partition. 
If one disk fails, the system is able to use the data from the other disk. 
 
The following facts apply to disk mirroring under Windows NT: 
 
- Only Windows NT Server can create and break mirror sets. 
 
- Mirrors are file system independent. Any partition using a file system 
that Windows NT recognizes or that is blank can be used to create a 
mirror. 
 
- Mirrors are not dependent on disk geometry. The only requirement is that 
free disk space used to place the mirror on be equal to or greater than 
the size of the primary partition. Mirroring is not restricted to a 
partition of identical geometry (size, number of heads, cylinders, 
tracks, sectors, etc.) nor is it restricted to a drive of the same type 
(IDE, ESDI, SCSI, etc.). 
 
- Primary and mirror partitions must be on separate hard disk drives. They 
cannot be on the same physical hard disk drive. 
 
- Whether the two hard disks containing the primary and mirrored 
partitions are on the same or different disk controllers, Windows NT 
still defines this as mirroring and makes no distinction. (Placing the 
disks on separate controllers is sometimes referred to as disk 
duplexing.) 
 
- A single mirror set is limited to two hard disks only. Use disk striping 
with parity if fault tolerance over more than two disks is needed. 
 
- Mirror sets are invisible to the user. When a mirror set is created, 
both partitions are assigned the same drive letter. 
 
- Mirroring is the only Windows NT fault tolerant option available for use 
on boot and system partitions. 
 
- If the boot or system partition is mirrored and the primary partition is 
damaged, the computer can boot off the secondary or mirror partition by 
using a fault tolerant boot floppy disk. See the Concepts and Planning 
Guide or online documentation for information on how to create a fault 
tolerant boot floppy disk. 
 
- Only the Windows NT Server installation that created the mirror set will 
normally recognize it. Other operating systems will not recognize the 
mirrored partition. MS-DOS will identify the partitions of the mirror as 
"Non-DOS" partitions. Windows NT and other installations of Windows NT 
Server will identify the primary and mirror partitions as having an 
"Unknown" file system type in Disk Administrator. 
 
NOTE: Windows NT and other installations of Windows NT Server can 
recognize a mirror set created by Windows NT Server by restoring disk 
configuration information. 
 
- A new installation of Windows NT cannot be installed on an existing 
mirror set. During setup, when selecting the partition to install 
Windows NT on, setup identifies the mirror set as "Windows NT Fault 
Tolerance." If you attempt to select this partition for installation, a 
message appears, stating that Windows NT does not recognize this 
partition, and it must be deleted for setup to use it. 
 
- The fault tolerance driver makes the loss of one partition in a mirror 
set invisible; you will be able to read from and write to the remaining 
partition as if the mirror set was healthy. However, if only one 
partition of a mirror set is functioning, then it is no longer fault 
tolerant. Loss of the remaining partition will result in an 
unrecoverable loss of all data in the mirror set. 
 
- A key to determining the condition of a mirror set is the status bar in 
Disk Administrator. When you select one of the partitions of a mirror 
set, Disk Administrator displays information about the mirror in the 
lower left corner of the window. For example, "Mirror set #0 [HEALTHY]" 
indicates the status of mirror set #0 is healthy. Other status 
indicators include: 
 
[NEW] appears immediately after the mirror set has been created in 
Disk Administrator, but before shutting down the system and actual 
generation of the mirror begins. 
 
[REGENERATING] is displayed when generation of the mirror set by the 
system has been started but is not yet complete. 
 
[RECOVERABLE] appears when either one of the partitions in the set 
has been lost but the other partition is undamaged. This message 
also appears when one partition loses synchronization with the other. 
 
- No loss in performance occurs when a member of a mirror set fails. 
 
- Disk mirroring provides better overall write performance than striping 
with parity and better read performance in the event of a drive failure. 
 
Additional query words: prodnt tshoot repair 
====================================================================== 
Keywords : ntfault kbother 
Version : 3.1 3.5 3.51 4.0 
Platform : WINDOWS 
============================================================================= 
Copyright Microsoft Corporation 1998.

SRG · Jun 2, 1999

PSS ID Number: Q130921 
Article last modified on 04-10-1997 
 
3.5 
 
WinNT 
 
 
====================================================================== 
------------------------------------------------------------------------- 
The information in this article applies to: 
 
- Microsoft Windows NT Workstation version 3.5 
- Microsoft Windows NT Server version 3.5 
------------------------------------------------------------------------- 
 
SUMMARY 
======= 
 
To create a fault tolerance floppy disk for recovering from a failed boot 
mirror partition, you may need to correct hardware identifier on the arc 
path name in the BOOT.INI file. 
 
The following are only two valid options to specify the arc name that 
identifies the disk/controller type: 
 
- SCSI(x)disk

rdisk(z)partition(a) 
- Multi(x)disk

rdisk(z)partition(a) 
 
SCSI indicates a SCSI disk drive is connected to a SCSI adapter whose BIOS 
has not been loaded. 
 
Multi can indicate a non-SCSI disk drive supported by either the ATDISK.SYS 
or ABIOSDSK.SYS driver, or a SCSI disk drive supported by a SCSI BIOS that 
loads when the SCSI adapter detects a bootable device on the lowest SCSI ID 
on most SCSI adapters. 
 
MORE INFORMATION 
================ 
 
Intel (x86) computers running Windows NT Server use the Multi option as the 
default hardware identifier for the primary bootable disk drive. 
This is due to the SCSI BIOS, ATDISK.SYS driver, or ABIOSDSK.SYS driver 
support. 
 
If the system is using a SCSI adapter and the primary boot drive of a 
mirror set fails or becomes inaccessible and the SCSI adapter BIOS does not 
load, the Multi identifier option will fail to locate the healthy mirror 
drive. As a result, the BOOT.INI file on the Fault Tolerance floppy disk 
will require the use of the SCSI option to boot the remaining mirror drive. 
 
NOTE: The SCSI identifier option should only be used when the SCSI adapter 
BIOS is not loaded. Refer to the Concepts and Planning Guide, p.163 for ARC 
path variable specifications. 
 
Additional query words: prodnt 
====================================================================== 
Keywords : kbusage ntfault 
Version : 3.5 
Platform : WinNT 
============================================================================= 
Copyright Microsoft Corporation 1997.

SRG · Jun 2, 1999

I have used this before it does work. If the drives are hot plugable then you "should" be able to just swap a new drive in then go the the disk administrator and pick regenerate. I ahve always shut the server down. removed the old drive rebooted with the other drive and recreated the mirror. I jumped from not hot swap drives to a raid controllers so I nexer worked RAID and hot swap under NT. Good Luck.

Ghost · Jun 2, 1999

SRG, 
 
Thanks a lot for all the help! 
 
Ghost

Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

NT Replication feature

Ghost

MIS

SRG

MIS

Ghost

MIS

SRG

MIS

SRG

MIS

SRG

MIS

Ghost

MIS

Similar threads

Part and Inventory Search

Sponsor