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Q96735: Hardware/Software Requirements for Fault Tolerance

Article: Q96735
Product(s): Microsoft LAN Manager
Version(s): 
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 19-FEB-2002

SUMMARY
=======

This article discusses basic requirements for fault tolerance. It also addresses
specific hardware issues such as IDE drives, Micro Channel and Compaq EISA
machine configurations, as well as some less common software issues such as
third party .BID files, LAN Manager's Network Productivity Pack, and unique boot
mirroring options.

IDE DRIVES
----------

The system must have at least two hard drives, preferably not IDE. (IDE =
integrated device electronics: a type of disk drive that does not need a
separate adapter card because it has resident controller electronics.) IDE
drives can hang the server if they experience a massive failure such as loss of
data cable or power connection.

NO PROPRIETARY DRIVE USE
------------------------

The system must not be using the drives in a proprietary manner. For example: IBM
Micro Channel machines apparently place IML microcode required for booting on
the boot drive. This conflicts with fault tolerance and makes it impossible to
boot from the mirror of the boot drive. On these types of machines, fault
tolerance seems to install and work successfully, but in the event of failure
the mirror will not boot.

EISA CONFIGURATION PARTITION
----------------------------

Compaq's EISA machines have a special partition for storing EISA configuration
information, and although fault tolerance has been successfully implemented on a
Prosignia using an Adaptec 1742 controller, and the mirror made bootable with
FTBOOT, this EISA configuration partition was not mirrored. Testing indicates
that you can reinstall the EISA configuration partition onto the former mirror
from diskette.

However, in testing with the Systempro/XL, FTSETUP's "View" option reported the
status of the C: drive as "Cannot mirror" when the EISA Configuration Partition
was installed. Removing this partition allowed the boot drive to be mirrored
successfully.

MIRRORING DRIVE MUST BE RAW
---------------------------

The drive becoming the mirror must be raw (not formatted, not partitioned). In
cases where setting up fault tolerance interferes with drive lettering, it often
is the case that a second drive has been installed and then
partitioned/formatted. If you create a primary partition on a new drive in
FDISKPM, drive letters are reassigned if there are extended partitions on the
other drives.

OS/2 1.3 AND LADDR
------------------

The system must be running OS/2 version 1.3 and using a LADDR disk driver either
supplied with it or by a third party source. HPFS must be on the partition to be
mirrored (FAT drives can be selected for mirroring but the process reformats
them to HPFS). The partition(s) to be mirrored/duplexed must not take 100
percent of the drive. For smaller drives, 2 MB of leftover unpartitioned space
may be enough. For larger drives, 2 to 5 percent free space would be a better
amount to use. OS/2 installation does not prompt for a partition size if the
disk is already partitioned, so if a disk's partition already uses 100 percent
of its capacity you must either delete the partition or repartition the disk
using MS-DOS before starting the installation process.

3RD PARTY .BID FILES
--------------------

If third party .BID files are being used for the disk, then copy them to the HPFS
recovery disks as well as to the installation disks--they are needed during the
recovery process.

LM VERSIONS EARLIER THAN 2.2
----------------------------

For versions of LAN Manager earlier than 2.2, the mirror of the boot partition
must end up with only one partition on it. A disk with an HPFS boot partition
and an additional FAT partition has been successfully mirrored and the boot
partition recovered when the primary drive was removed from the system.
Mirroring a boot partition onto a smaller drive is possible, but this requires
that the boot partition be smaller than the mirror drive--small enough to fit
onto it and leave room for fault tolerance (2 MB of unpartitioned space for
smaller drives, 2% - 5% for larger). Once the boot partition has been mirrored,
the remaining space on the primary drive can be partitioned. Because fault
tolerance makes decisions about what raw space to use for mirroring, you must
make sure that the boot mirror contains only one partition. As a result, these
configurations are generally not recommended unless you have a thorough
understanding of how mirroring is done.

For these versions of LAN Manager, a boot drive with two HPFS partitions will
seem to mirror successfully, but attempting FTBOOT after removing the primary
drive returns a message that the disk was improperly configured for recovery.

LM VERSIONS 2.2 AND LATER
-------------------------

For LAN Manager 2.2, mirroring of the boot drive with more than one partition is
possible.

If you are using the Network Productivity Pack, copy FTBOOT.EXE from the LAN
Manager 2.1 disks to the HPFS recovery disks. FTBOOT.EXE was not included on the
distribution disks of the Network Productivity Pack.

If you have LAN Manager 2.2 and the date of FTBOOT.EXE is earlier than March
1993, then you need to get a newer version that fixed a bug causing Trap Ds and
Cs on reboot after using FTBOOT. This fix was included in the LM22 Patch.

Additional query words: 2.10 2.10a 2.20 2.1 2.1a 2.2

======================================================================
Keywords          : kbnetwork 

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