DBA: Linux   DOWNLOAD Oracle Database 10g   TAGS linux, rac, clustering All Build Your Own Oracle RAC 10g Release 2 Cluster on Linux and FireWire by Jeffrey Hunter Learn how to set up and configure an Oracle RAC 10g Release 2 development cluster for less than US$1,800. For development and testing only; production deployments will not be supported! Updated March 2007 Contents Introduction Oracle RAC 10g Overview Shared-Storage Overview FireWire Technology Hardware & Costs Install the Linux Operating System Network Configuration Obtain & Install FireWire Modules Create "oracle" User and Directories Create Partitions on the Shared FireWire Storage Device Configure the Linux Servers for Oracle Configure the hangcheck-timer Kernel Module Configure RAC Nodes for Remote Access All Startup Commands for Each RAC Node Check RPM Packages for Oracle 10g Release 2 Install & Configure Oracle Cluster File System (OCFS2) Install & Configure Automatic Storage Management (ASMLib 2.0) Download Oracle 10g RAC Software Install Oracle 10g Clusterware Software Install Oracle 10g Database Software Install Oracle10g Companion CD Software Create TNS Listener Process Create the Oracle Cluster Database Verify TNS Networking Files Create / Alter Tablespaces Verify the RAC Cluster & Database Configuration Starting / Stopping the Cluster Transparent Application Failover - (TAF) Conclusion Acknowledgements Downloads for this guide: CentOS Enterprise Linux 4.2 Oracle Cluster File System Release 2 - (1.2.3-1) - Single Processor / SMP / Hugemem Oracle Cluster File System Releaase 2 Tools - (1.2.1-1) - Tools / Console Oracle Database 10g Release 2 EE, Clusterware, Companion CD - (10.2.0.1.0) Precompiled RHEL4 FireWire Modules - (2.6.9-22.EL) ASMLib 2.0 Driver - (2.6.9-22.EL / 2.0.3-1) - Single Processor / SMP / Hugemem ASMLib 2.0 Library and Tools - (2.0.3-1) - Driver Support Files / Userspace Library

One of the most efficient ways to become familiar with Oracle Real Application Clusters (RAC) 10g technology is to have access to an actual Oracle RAC 10g cluster. There's no better way to understand its benefits—including fault tolerance, security, load balancing, and scalability—than to experience them directly.

Unfortunately, for many shops, the price of the hardware required for a typical production RAC configuration makes this goal impossible. A small two-node cluster can cost from US$10,000 to well over US$20,000. That cost would not even include the heart of a production RAC environment—typically a storage area network—which can start at US$10,000.

For those who want to become familiar with Oracle RAC 10g without a major cash outlay, this guide provides a low-cost alternative to configuring an Oracle RAC 10g Release 2 system using commercial off-the-shelf components and downloadable software at an estimated cost of US$1,200 to US$1,800. The system involved comprises a dual-node cluster (each with a single processor) running Linux (CentOS 4.2) with a shared disk storage based on IEEE1394 (FireWire) drive technology.

This guide will mark the last in a series to make use of FireWire technology as the shared storage medium in order to build an inexpensive Oracle RAC 10g system. The most current published version takes advantage of iSCSI; more specifically, it explains how to build a network storage server using Openfiler. Powered by rPath Linux, Openfiler is a free browser-based network storage management utility that delivers file-based Network Attached Storage (NAS) and block-based Storage Area Networking (SAN) in a single framework. Openfiler supports CIFS, NFS, HTTP/DAV, FTP, however; I will only be making use of its iSCSI capabilities to implement an inexpensive SAN for the shared storage component required by OracleRAC 10g.

Please note, that this is not the only way to build a low-cost Oracle RAC 10g system. I have worked on other solutions that utilize an implementation based on SCSI rather than FireWire for shared storage. In most cases, SCSI will cost more than a FireWire solution where an inexpensive SCSI configuration will consist of:

• SCSI Controller:Two SCSI controllers priced from $20 (Adaptec AHA-2940UW) to $220 (Adaptec 39320A-R) each
• SCSI Enclosure: $70 - (Inclose 1 Bay 3.5" U320 SCSI Case)
• SCSI Hard Drive: $140 - (36GB 15K 68p U320 SCSI Hard Drive)
• SCSI Cables: Two SCSI cables priced at $20 each - (3ft External HD68 to HD68 U320 Cable)

Keep in mind that some motherboards may already include built-in SCSI controllers.

It is important to note that this configuration should never be run in a production environment and that it is not supported by Oracle or any other vendor. In a production environment, fibre channel—the high-speed serial-transfer interface that can connect systems and storage devices in either point-to-point or switched topologies—is the technology of choice. FireWire offers a low-cost alternative to fibre channel for testing and development, but it is not ready for production.

The Oracle9i and Oracle 10g Release 1 guides used raw partitions for storing files on shared storage, but here we will make use of the Oracle Cluster File System Release 2 (OCFS2) and Oracle Automatic Storage Management (ASM) feature. The two Linux servers will be configured as follows:

Note that with Oracle Database 10g Release 2 (10.2), Cluster Ready Services, or CRS, is now called Oracle Clusterware.

Starting with Oracle Database 10g Release 2 (10.2), Oracle Clusterware should be installed in a separate Oracle Clusterware home directory which is non-release specific. This is a change to the Optimal Flexible Architecture (OFA) rules. You should not install Oracle Clusterware in a release-specific Oracle home mount point, (/u01/app/oracle/product/10.2.0/... for example), as succeeding versions of Oracle Clusterware will overwrite the Oracle Clusterware installation in the same path. Also, If Oracle Clusterware 10g Release 2 (10.2) detects an existing Oracle Cluster Ready Services installation, then it overwrites the existing installation in the same path.

The Oracle Clusterware software will be installed to /u01/app/oracle/product/crs on each of the nodes that make up the RAC cluster. However, the Clusterware software requires that two of its files—the Oracle Cluster Registry (OCR) file and the Voting Disk file—be shared with all nodes in the cluster. These two files will be installed on shared storage using OCFS2. It is possible (but not recommended by Oracle) to use RAW devices for these files; however, it is not possible to use ASM for these two Clusterware files.

The Oracle Database 10g Release 2 software will be installed into a separate Oracle Home, namely /u01/app/oracle/product/10.2.0/db_1, on each of the nodes that make up the RAC cluster. All the Oracle physical database files (data, online redo logs, control files, archived redo logs), will be installed to different partitions of the shared drive being managed by ASM. (The Oracle database files can just as easily be stored on OCFS2. Using ASM, however, makes the article that much more interesting!)

Note: This article is only designed to work as documented with absolutely no substitutions. If you are looking for an example that takes advantage of Oracle RAC 10g Release 1 with RHEL 3, click here.

If you are looking for a version that takes advantage of RHEL 4 with iSCSI and OpenFiler for shared storage, click here.

For the previously published Oracle9i RAC version of this guide, click here.

Oracle RAC, introduced with Oracle9i, is the successor to Oracle Parallel Server (OPS). RAC allows multiple instances to access the same database (storage) simultaneously. It provides fault tolerance, load balancing, and performance benefits by allowing the system to scale out, and at the same time—because all nodes access the same database—the failure of one instance will not cause the loss of access to the database.

At the heart of Oracle RAC is a shared disk subsystem. All nodes in the cluster must be able to access all of the data, redo log files, control files and parameter files for all nodes in the cluster. The data disks must be globally available to allow all nodes to access the database. Each node has its own redo log and control files but the other nodes must be able to access them in order to recover that node in the event of a system failure.

One of the bigger differences between Oracle RAC and OPS is the presence of Cache Fusion technology. In OPS, a request for data between nodes required the data to be written to disk first, and then the requesting node could read that data. With cache fusion, data is passed along a high-speed interconnect using a sophisticated locking algorithm.

Not all clustering solutions use shared storage. Some vendors use an approach known as a federated cluster, in which data is spread across several machines rather than shared by all. With Oracle RAC 10g, however, multiple nodes use the same set of disks for storing data. With Oracle RAC, the data files, redo log files, control files, and archived log files reside on shared storage on raw-disk devices, a NAS, a SAN, ASM, or on a clustered file system. Oracle's approach to clustering leverages the collective processing power of all the nodes in the cluster and at the same time provides failover security.

Pre-configured Oracle10g RAC solutions are available from vendors such as Dell, IBM and HP for production environments. This article, however, focuses on putting together your own Oracle10g RAC environment for development and testing by using Linux servers and a low cost shared disk solution; FireWire.

For more background about Oracle RAC, visit the Oracle RAC Product Center on OTN.

Fibre Channel is one of the most popular solutions for shared storage. As I mentioned previously, Fibre Channel is a high-speed serial-transfer interface used to connect systems and storage devices in either point-to-point or switched topologies. Protocols supported by Fibre Channel include SCSI and IP.

Fibre Channel configurations can support as many as 127 nodes and have a throughput of up to 2.12 gigabits per second. Fibre Channel, however, is very expensive; the switch alone can start at US$1,000 and high-end drives can reach prices of US$300. Overall, a typical Fibre Channel setup (including cards for the servers) costs roughly US$10,000.

A less expensive alternative to Fibre Channel is SCSI. SCSI technology provides acceptable performance for shared storage, but for administrators and developers who are used to GPL-based Linux prices, even SCSI can come in over budget at around US$2,000 to US$5,000 for a two-node cluster.

Another popular solution is the Sun NFS (Network File System) found on a NAS. It can be used for shared storage but only if you are using a network appliance or something similar. Specifically, you need servers that guarantee direct I/O over NFS, TCP as the transport protocol, and read/write block sizes of 32K.

Developed by Apple Computer and Texas Instruments, FireWire is a cross-platform implementation of a high-speed serial data bus. With its high bandwidth, long distances (up to 100 meters in length) and high-powered bus, FireWire is being used in applications such as digital video (DV), professional audio, hard drives, high-end digital still cameras and home entertainment devices. Today, FireWire operates at transfer rates of up to 800 megabits per second while next generation FireWire calls for speeds to a theoretical bit rate to 1600 Mbps and then up to a staggering 3200 Mbps. That's 3.2 gigabits per second. This will make FireWire indispensable for transferring massive data files and for even the most demanding video applications, such as working with uncompressed high-definition (HD) video or multiple standard-definition (SD) video streams.

The following chart shows speed comparisons of the various types of disk interfaces. For each interface, I provide the maximum transfer rates in kilobits (kb), kilobytes (KB), megabits (Mb), megabytes (MB), gigabits (Gb), and gigabytes (GB) per second. As you can see, the capabilities of IEEE1394 compare very favorably with other disk interface and network technologies that are currently available today.

The hardware used to build our example Oracle10g RAC environment consists of two Linux servers and components that can be purchased at any local computer store or over the Internet.

Now that we know the hardware that will be used in this example, let's take a conceptual look at what the environment looks like:

As we start to go into the details of the installation, keep in mind that most tasks will need to be performed on both servers. I will indicate at the beginning of each section whether or not the task(s) should be performed on both nodes or not.

This section provides a summary of the screens used to install the Linux operating system. This guide is designed to work with the Red Hat Enterprise Linux 4 AS/ES (RHEL4) operating environment. As an alternative, and what I used for this article, is CentOS 4.2: a free and stable version of the RHEL4 operating environment.

For more detailed installation instructions, it is possible to use the manuals from Red Hat Linux. I would suggest, however, that the instructions I have provided below be used for this configuration.

Before installing the Linux operating system on both nodes, you should have the FireWire and two NIC interfaces (cards) installed.

Also, before starting the installation, ensure that the FireWire drive (our shared storage drive) is NOT connected to either of the two servers. You may also choose to connect both servers to the FireWire drive and simply turn the power off to the drive. Although none of this is mandatory, it is how I will be performing the installation and configuration for this article.

Download the following ISO images for CentOS 4.2:

• CentOS-4.2-i386-bin1of4.iso   (618 MB)
• CentOS-4.2-i386-bin2of4.iso   (635 MB)
• CentOS-4.2-i386-bin3of4.iso   (639 MB)
• CentOS-4.2-i386-bin4of4.iso   (217 MB)
  

After downloading and burning the CentOS images (ISO files) to CD, insert CentOS Disk #1 into the first server (linux1 in this example), power it on, and answer the installation screen prompts as noted below. After completing the Linux installation on the first node, perform the same Linux installation on the second node while substituting the node name linux1 for linux2 and the different IP addresses where appropriate.

Boot Screen
The first screen is the CentOS Enterprise Linux boot screen. At the boot: prompt, hit [Enter] to start the installation process.

Media Test
When asked to test the CD media, tab over to [Skip] and hit [Enter]. If there were any errors, the media burning software would have warned us. After several seconds, the installer should then detect the video card, monitor, and mouse. The installer then goes into GUI mode.

Welcome to CentOS Enterprise Linux
At the welcome screen, click [Next] to continue.

Language / Keyboard Selection
The next two screens prompt you for the Language and Keyboard settings. Make the appropriate selections for your configuration.

Installation Type
Choose the [Custom] option and click [Next] to continue.

Disk Partitioning Setup
Select [Automatically partition] and click [Next] continue.

If there were a previous installation of Linux on this machine, the next screen will ask if you want to "remove" or "keep" old partitions. Select the option to [Remove all partitions on this system]. Also, ensure that the [hda] drive is selected for this installation. I also keep the checkbox [Review (and modify if needed) the partitions created] selected. Click [Next] to continue.

You will then be prompted with a dialog window asking if you really want to remove all partitions. Click [Yes] to acknowledge this warning.

Partitioning
The installer will then allow you to view (and modify if needed) the disk partitions it automatically selected. In almost all cases, the installer will choose 100MB for /boot, double the amount of RAM for swap, and the rest going to the root (/) partition. I like to have a minimum of 1GB for swap. For the purpose of this install, I will accept all automatically preferred sizes. (Including 2GB for swap since I have 1GB of RAM installed.)

Starting with RHEL 4, the installer will create the same disk configuration as just noted but will create them using the Logical Volume Manager (LVM). For example, it will partition the first hard drive (/dev/hda for my configuration) into two partitions—one for the /boot partition (/dev/hda1) and the remainder of the disk dedicate to a LVM named VolGroup00 (/dev/hda2). The LVM Volume Group (VolGroup00) is then partitioned into two LVM partitions - one for the root filesystem (/) and another for swap. I basically check that it created at least 1GB of swap. Since I have 1GB of RAM installed, the installer created 2GB of swap. Saying that, I just accept the default disk layout.

Boot Loader Configuration
The installer will use the GRUB boot loader by default. To use the GRUB boot loader, accept all default values and click [Next] to continue.

Network Configuration
I made sure to install both NIC interfaces (cards) in each of the Linux machines before starting the operating system installation. This screen should have successfully detected each of the network devices.

First, make sure that each of the network devices are checked to [Active on boot]. The installer may choose to not activate eth1.

Second, [Edit] both eth0 and eth1 as follows. You may choose to use different IP addresses for both eth0 and eth1 and that is OK. If possible, try to put eth1 (the interconnect) on a different subnet than eth0 (the public network):

eth0:
- Check off the option to [Configure using DHCP]
- Leave the [Activate on boot] checked
- IP Address: 192.168.1.100
- Netmask: 255.255.255.0

eth1:
- Check off the option to [Configure using DHCP]
- Leave the [Activate on boot] checked
- IP Address: 192.168.2.100
- Netmask: 255.255.255.0

Continue by setting your hostname manually. I used "linux1" for the first node and "linux2" for the second one. Finish this dialog off by supplying your gateway and DNS servers.

Firewall
On this screen, make sure to select [No firewall] and click [Next] to continue. You may be prompted with a warning dialog about not setting the firewall. If this occurs, simply hit [Proceed] to continue.

Additional Language Support/Time Zone
The next two screens allow you to select additional language support and time zone information. In almost all cases, you can accept the defaults.

Set Root Password
Select a root password and click [Next] to continue.

Package Group Selection
Scroll down to the bottom of this screen and select [Everything] under the "Miscellaneous" section. Click [Next] to continue.

Please note that the installation of Oracle does not require all Linux packages to be installed. My decision to install all packages was for the sake of brevity. Please see section Section 15 ("Check RPM Packages for Oracle 10g Release 2") for a more detailed look at the critical packages required for a successful Oracle installation.

Note that with some RHEL4 distributions, you will not get the "Package Group Selection" screen by default. There, you are asked to simply "Install default software packages" or "Customize software packages to be installed". Select the option to "Customize software packages to be installed" and click [Next] to continue. This will then bring up the "Package Group Selection" screen. Now, scroll down to the bottom of this screen and select [Everything] under the "Miscellaneous" section. Click [Next] to continue.

About to Install
This screen is basically a confirmation screen. Click [Next] to start the installation. During the installation process, you will be asked to switch disks to Disk #2, Disk #3, and then Disk #4. Click [Continue] to start the installation process.

Note that with CentOS 4.2, the installer will ask to switch to Disk #2, Disk #3, Disk #4, Disk #1, and then back to Disk #4.

Graphical Interface (X) Configuration
With most RHEL4 distributions (not the case with CentOS 4.2), when the installation is complete, the installer will attempt to detect your video hardware. Ensure that the installer has detected and selected the correct video hardware (graphics card and monitor) to properly use the X Windows server. You will continue with the X configuration in the next serveral screens.

Congratulations
And that's it. You have successfully installed CentOS Enterprise Linux on the first node (linux1). The installer will eject the CD from the CD-ROM drive. Take out the CD and click [Exit] to reboot the system.

When the system boots into Linux for the first time, it will prompt you with another Welcome screen. The following wizard allows you to configure the date and time, add any additional users, testing the sound card, and to install any additional CDs. The only screen I care about is the time and date (and if you are using CentOS 4.x, the monitor/display settings). As for the others, simply run through them as there is nothing additional that needs to be installed (at this point anyways!). If everything was successful, you should now be presented with the login screen.

Perform the same installation on the second node
After completing the Linux installation on the first node, repeat the above steps for the second node (linux2). When configuring the machine name and networking, ensure to configure the proper values. For my installation, this is what I configured for linux2:

First, make sure that each of the network devices are checked to [Active on boot]. The installer will choose not to activate eth1.

Second, [Edit] both eth0 and eth1 as follows:

eth0:
- Check off the option to [Configure using DHCP]
- Leave the [Activate on boot] checked
- IP Address: 192.168.1.101
- Netmask: 255.255.255.0

eth1:
- Check off the option to [Configure using DHCP]
- Leave the [Activate on boot] checked
- IP Address: 192.168.2.101
- Netmask: 255.255.255.0

Continue by setting your hostname manually. I used "linux2" for the second node. Finish this dialog off by supplying your gateway and DNS servers.

Note: Although we configured several of the network settings during the Linux installation, it is important to not skip this section as it contains critical steps that are required for the RAC environment.

Introduction to Network Settings

During the Linux O/S install you already configured the IP address and host name for each of the nodes. You now need to configure the /etc/hosts file as well as adjust several of the network settings for the interconnect.

Each node should have one static IP address for the public network and one static IP address for the private cluster interconnect. The private interconnect should only be used by Oracle to transfer Cluster Manager and Cache Fusion related data. Although it is possible to use the public network for the interconnect, this is not recommended as it may cause degraded database performance (reducing the amount of bandwidth for Cache Fusion and Cluster Manager traffic). For a production RAC implementation, the interconnect should be at least gigabit or more and only be used by Oracle.

Configuring Public and Private Network

In our two-node example, you need to configure the network on both nodes for access to the public network as well as their private interconnect.

The easiest way to configure network settings in RHEL4 is with the Network Configuration program. This application can be started from the command-line as the root user account as follows:

# su -
# /usr/bin/system-config-network &

Using the Network Configuration application, you need to configure both NIC devices as well as the /etc/hosts file. Both of these tasks can be completed using the Network Configuration GUI. Notice that the /etc/hosts settings are the same for both nodes.

Our example configuration will use the following settings: