Release 8.1.5 for Windows NT
A68813-01
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| Oracle8i
Parallel Server Getting Started
Release 8.1.5 for Windows NT A68813-01 |
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This chapter describes required pre-installation tasks.
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Note:
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Specific topics discussed are:
Because no true distributed file system support exists on
Windows NT, the mechanism Oracle uses to allow nodes running different
instances to access shared disks is to bypass the NT file system by using
raw partitions. Data files are stored on the raw partitions. The shared
disks are then a collection of unformatted raw devices.
A raw partition is a portion of a physical disk that is accessed
at the lowest possible level. I/O to a raw partition offers approximately
a 5% to 10% performance improvement over I/O to a partition with a file
system on it.
A raw partition is created when an extended partition is
created and logical partitions are assigned to it without applying any
formatting. The Windows NT Disk Administrator application allows you to
create an extended partition on a physical drive.
An extended partition points to raw space on the disk that
can be assigned multiple logical partitions for the database files. An
extended partition avoids the four-partition limit by allowing you to define
large numbers of logical partitions to accommodate applications using Oracle8
Enterprise Edition. Logical partitions can then be given symbolic link
names to free up drive letters. We create an extended partition and link
the drive letters to symbolic link names "Step
1: Create an Extended Partition".
The Disk Administrator window shown below shows four
disks, two of the disks having an extended partition:
Windows NT defines each disk drive found at startup with the following naming convention:
where Harddiskm is the number of the physical drive, and Partitionn is a logical partition number, as shown in the Disk Administrator window (in Figure 3-1). Harddiskm starts at 0, and Partitionn starts at 1. Partition0 has a special meaning in that it has access to the whole disk. For example, the first logical partition (E:) on the second physical drive in Figure 3-1 has the following entry:
The first logical partition on a system (normally the C drive) has the following entry:
Raw partitions are of two types:
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Note: Although you can use physical disks, Oracle Corporation recommends using logical partitions and creating symbolic links (as described in section "Step 4: Assign Symbolic Links to Each Logical Partition"). |
A physical disk represents the entire disk. It points to
\Device\Harddiskx\Partition0. Windows NT automatically creates a
symbolic link name of \\.\PhysicalDriveX, where X is the
number corresponding to your hard disk drive number in the Disk Administrator.
The X matches the X in \Device\HarddiskX\Partition0.
\\.\PhysicalDriveX is automatically defined by Windows NT for every hard disk in the machine. For example, a machine with three hard disks will have the following names defined by Windows NT:
Internally, these names expand to:
\\.\PhysicalDrive0 = \Device\Harddisk0\Partition0
\\.\PhysicalDrive1 =\Device\Harddisk1\Partition0
\\.\PhysicalDrive2 =\Device\Harddisk2\Partition0
Partition0 is special in that it represents the entire physical
disk regardless of any partitioning scheme on that disk. On all disks recognized
by Windows NT, the Disk Administrator writes a signature on the first block
of all disks. To avoid overwriting that block, Oracle skips the first block
of a physical raw partition which is used for an Oracle data file.
A logical partition is a partition created by the Disk
Administrator that points to a A logical partition is a partition created
by the Disk Administrator that points to a drive other than \Device\Harddiskx\Partition0.
Logical partitions are initially assigned names with drive letters (\\.\drive_letter:)
and typically re-assigned symbolic link names (\\.\symbolic link name).
For example, \\.\D: may be assigned a symbolic link name of \\.\ops_sys1.
Regardless of whether a drive letter or symbolic link name is used, logical
partitions are defined to represent a specific partition in a disk rather
than the entire disk. Internally, these names may expand to:
\\.\D:= \Device\Harddisk2\Partition1
\\.\op_sys1= \Device\Harddisk3\Partition2
Drive letters can be assigned to specific partitions using
the Disk Administrator, while symbolic link names can be assigned
using the SETLINKS utility (shipped with the Parallel Server Option).
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Note: Oracle does not skip the first block of a logical raw partition used for an Oracle data file. |
Please consider the following when deciding which raw partition to use:
Question: What is the impact if I have created logical
partitions, but defined physical disk convention names for them. For example:
\\.\PhysicalDrivesys1 = \Device\Harddisk2\Partition1
\\.\PhysicalDriveusr1 =\Device\Harddisk3\Partition1
Answer: Oracle database will handle the data file
using the physical disk convention, even though it really is a logical
partition. This will not cause any data corruption or loss, as long as
you continue using the physical disk naming conventions. Oracle Corporation
recommends you convert to the logical partition at your earliest convenience.
See "Compatibility Issues".
Question: What is the impact if I have created logical
names representing Partition0. For example:
\\.\op_sys1 = \Device\Harddisk1\Partition0
Answer: This will pose severe problems, as the Disk
Administrator typically writes a signature into the first block of every
disk, and consequently may overwrite a portion of the data file header.
This may also cause data loss. Never use Partition0 with
the logical partition convention. See "Compatibility
Issues" for information on rebuilding your Oracle database with the
proper conventions.
Question: How do I transfer the contents of any raw
partition to a standard file system for backup purposes?
Answer: Use the Oracle provided OCOPY to copy data
to/from a raw partition for both physical and logical raw conventions.
See "Compatibility Issues" for further information.
The physical and logical partition conventions are not compatible
with one another due to the extra block that is skipped for physical raw
conventions. This also means you cannot simply do an OCOPY from a physical
disk to a logical partition, as the contents of these partitions are incompatible.
To convert from a physical convention to a logical convention, you must:
If your database installation uses physical disk conventions
with logical partitions, Oracle Corporation recommends converting to the
logical partition conventions at your earliest convenience using the steps
above.
Only one extended partition can be created per disk. You
can use the free space in the extended partition to create multiple logical
partitions or use all or part of it when creating volume sets or other
kinds of volumes for fault-tolerance purposes.
To create an extended partition:
Oracle recommends you use the entire disk.
The Disk Administrator displays the minimum and maximum
sizes for the extended partition:
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Note: Changes you have made are not saved until you choose Commit Changes Now from the Partition menu or quit the Disk Administrator. |
The extended partition is created.
Note the lines now display diagonally from top left to bottom
right, indicating the partition is an extended partition.
After an extended drive is created, you must assign logical
partitions to it. Logical partitions are assigned letters of the alphabet.
The Oracle Database Configuration Assistant requires at least
12 partitions for a two-node cluster's tablespaces.
Shown below are the number of partitions that must be created
and the minimum size that the Oracle Database Configuration Assistant expects.
When creating a raw partition, ensure that the size is a little larger
than indicated below to account for future growth.
To create logical partitions in an extended partition:
The Disk Administrator window displays the minimum
and maximum sizes for the logical partition:
A confirmation dialog appears, informing you changes have been made to the disk.
A dialog box appears, informing you the disks have been updated successfully.
On all nodes except the node you created the logical partitions, a dialog box appears, informing you the disk configuration has been detected. If you do not see this dialog box, it does not mean the disk configuration has not changed.
The extended partition and the logical partitions are now
seen by all of the nodes.
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Note: The hard disks that access the shared area may be different from node to node. The logical partitions, however, that reside on the hard disks must be identical on all nodes. |
For example, Node 1 may look like:
On Node 1, the logical partition E is defined as \Device\Harddisk1\Partition1.
On Node 2, it is defined as \Device\Harddisk2\Partition1. Even though these
map to different disks, they map to the same space on the shared disk.
To free up other drive letters for other purposes, such as
mapping network drives, it is important to also unassign the drive letters
from the logical partitions on each partition. Oracle8i Parallel Server
does not need to access a partition through a drive letter.
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Note: If your disks have been previously configured, the logical partitions may already be unassigned. If this is the case, you can skip to Step 6 of this procedure. |
To unassign drive letters:
The Assign Drive Letter dialog box appears:
A confirmation dialog box appears.
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Note: The hard disks that access the shared area may be different from node to node. The logical partitions, however, that reside on the hard disks must be identical from node to node. |
Oracle Corporation recommends using a worksheet similar
to the one below.
| Node 1 | Node 2 | Node 3 | Node 4 | |
|---|---|---|---|---|
|
Hard DiskX |
Partitions X-X |
Partitions X-X |
Partitions X-X |
Partitions X-X |
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Hard DiskX |
Partitions X-X |
Partitions X-X |
Partitions X-X |
Partitions X-X |
For example, the worksheet for the Disk Administrator
windows shown in Figure 3-2 and Figure
3-3 would look like:
| Node 1 | Node 2 | |
|---|---|---|
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Hard Disk1 |
Partitions 1-6 |
n/a |
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Hard Disk2 |
Partitions 1-3 |
Partitions 1-6 |
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Hard Disk3 |
n/a |
Partitions 1-3 |
The Disk Administrator application exits.
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Note: If you do not plan create a database during a Typical or Custom install and do not want to use the Oracle Configuration Database Assistant, you do not have to perform this procedure. Instead, proceed to Oracle8i Parallel Server Setup and Configuration Guide, Chapter 3, "Installing Oracle8i Parallel Server" to install, then to "Starting the Database in Parallel Mode". |
The Oracle SETLINKS utility creates symbolic links to raw
logical partitions.
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Note: It is not required to run this utility prior to installation if the Custom installation type was chosen and:
See Chapter 4, "Configuring Oracle8i Parallel Server", for information about running SETLINKS during a manual configuration. |
For example, with the SETLINKS utility, you can create a symbolic link called OP_log1 to the second logical partition on the second physical disk:
OP_log1_1 \Device\Harddisk2\Partition2
The Oracle8i Enterprise Edition CD-ROM contains the
following ASCII files (in the \OPS_PREINSTALL directory), with symbolic
link names already associated with raw partitions. These files should be
used as templates to create your own *.TBL files.
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Figure 3-4 shows TEMPLATE.TBL,
which contains symbolic links to support a four-node cluster.
To create symbolic links to the logical partitions, perform the following steps on each node:
You can use a worksheet similar the one below to assist
with the process:
C:\> CD TEMP_DIR C:\> TEMP_DIR> SETLINKS /F:FILE.TBL
SETLINKS maps the drives to the symbolic label names. For example:
Oracle Corporation. Copyright (c) 1998. All rights reserved. Created Link: Created Link:OP_dr = Device:\Device\Harddisk1\Partition1 Created Link:OP_sys1 = Device:\Device\Harddisk1\Partition2 Created Link:OP_tmp1 = Device:\Device\Harddisk1\Partition3 Created Link:OP_rbs1 = Device:\Device\Harddisk1\Partition4 Created Link:OP_oemrep1 = Device:\Device\Harddisk1\Partition5 Created Link:OP_usr1 = Device:\Device\Harddisk1\Partition6 Created Link:OP_ctl1 = Device:\Device\Harddisk2\Partition1 Created Link:OP_ctl2 = Device:\Device\Harddisk2\Partition2 Created Link:OP_log1_1 = Device:\Device\Harddisk2\Partition3 Created Link:OP_log1_2 = Device:\Device\Harddisk2\Partition4 Created Link:OP_log2_1 = Device:\Device\Harddisk2\Partition5 Created Link:OP_log2_2 = Device:\Device\Harddisk2\Partition6 Dos devices updated successfully.
C:\> TEMP_DIR> SETLINKS /D
SETLINKS shows how the symbolic link names have been mapped:
Oracle Corporation. Copyright (c) 1999. All rights reserved. OP_dr = \Device\Harddisk1\Partition1 OP_sys1 = \Device\Harddisk1\Partition2 OP_tmp1 = \Device\Harddisk1\Partition3 OP_rbs1 = \Device\Harddisk1\Partition4 ...
To remove an existing symbolic link:
List a symbolic link without a device path in the *.TBL file.
For example:
OP_dr OP_sys1 \Device\HarddiskX\PartitionX OP_tmp1 \Device\HarddiskX\PartitionX OP_rbs1 \Device\HarddiskX\PartitionX OP_indx1 \Device\HarddiskX\PartitionX OP_oemrep1 \Device\HarddiskX\PartitionX OP_usr1 \Device\HarddiskX\PartitionX OP_ctl1 \Device\HarddiskX\PartitionX OP_ctl2 \Device\HarddiskX\PartitionX OP_log1_1 \Device\HarddiskX\PartitionX OP_log1_2 \Device\HarddiskX\PartitionX OP_log2_1 \Device\HarddiskX\PartitionX OP_log2_2 \Device\HarddiskX\PartitionX
This removes the OP_dr link and creates the other links specified.
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Copyright © 1999 Oracle Corporation. All Rights Reserved. |
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