This chapter includes storage administration tasks that you should complete if you intend to use Oracle Clusterware with Oracle Real Application Clusters (Oracle RAC).
This chapter contains the following topics:
This section describes supported options for storing Oracle Database files, and data files.
See Also:The Oracle Certify site for a list of supported vendors for Network Attached Storage options:
There are three ways of storing Oracle Database and recovery files:
Automatic Storage Management: Automatic Storage Management (ASM) is an integrated, high-performance database file system and disk manager for Oracle Database files. It performs striping and mirroring of database files automatically.
A supported shared file system: Supported file systems include the following:
A supported cluster file system, such as Sun StorEdge QFS. Note that if you intend to use a cluster file system for your data files, then you should create partitions large enough for the database files when you create partitions for Oracle Clusterware.
See Also:The Certify page on OracleMetalink for supported cluster file systems
NAS Network File System (NFS) listed on Oracle Certify: Note that if you intend to use NFS for your data files, then you should create partitions large enough for the database files when you create partitions for Oracle Clusterware.
See Also:The Certify page on OracleMetalink for supported Network Attached Storage (NAS) devices, and supported cluster file systems
Block or Raw Devices: A partition is required for each database file. If you do not use ASM, then for new installations on raw devices, you must use a custom installation.
For all installations, you must choose the storage option that you want to use for Oracle Database files, or for Oracle Clusterware with Oracle RAC. If you want to enable automated backups during the installation, then you must also choose the storage option that you want to use for recovery files (the Fast recovery area). You do not have to use the same storage option for each file type.
For single-instance Oracle Database installations using Oracle Clusterware for failover, you must use ASM or shared raw disks if you do not want the failover processing to include dismounting and remounting of local file systems.
The following table shows the storage options supported for storing Oracle Database files and Oracle Database recovery files. Oracle Database files include data files, control files, redo log files, the server parameter file, and the password file.
Note:For the most up-to-date information about supported storage options for Oracle RAC installations, refer to the Certify pages on the OracleMetaLink Web site:
|Storage Option||File Types Supported|
Automatic Storage Management
Supported cluster file system
NFS file system
Note: Requires a certified NAS device
Shared raw devices
Use the following guidelines when choosing the storage options that you want to use for each file type:
You can choose any combination of the supported storage options for each file type provided that you satisfy all requirements listed for the chosen storage options.
Oracle recommends that you choose Automatic Storage Management (ASM) as the storage option for database and recovery files.
For Standard Edition Oracle RAC installations, ASM is the only supported storage option for database or recovery files.
You cannot use ASM to store Oracle Clusterware files, because these files must be accessible before any ASM instance starts.
If you intend to use ASM with Oracle RAC, and you are configuring a new ASM instance, then your system must meet the following conditions:
All nodes on the cluster have the 11g release 1 (11.1) version of Oracle Clusterware installed.
Any existing ASM instance on any node in the cluster is shut down.
If you intend to upgrade an existing Oracle RAC database, or an Oracle RAC database with ASM instances, then you must ensure that your system meets the following conditions:
Oracle Universal Installer (OUI) and Database Configuration Assistant (DBCA) are run on the node where the Oracle RAC database or Oracle RAC database with ASM instance is located.
The Oracle RAC database or Oracle RAC database with an ASM instance is running on the same nodes that you intend to make members of the new cluster installation. For example, if you have an existing Oracle RAC database running on a three-node cluster, then you must install the upgrade on all three nodes. You cannot upgrade only 2 nodes of the cluster, removing the third instance in the upgrade.
See Also:Oracle Database Upgrade Guide for information about how to prepare for upgrading an existing database
If you do not have a storage option that provides external file redundancy, then you must configure at least three voting disk areas to provide voting disk redundancy.
After you have installed and configured Oracle Clusterware storage, and after you have reviewed your disk storage options for Oracle Database files, you must perform the following tasks in the order listed:
To use a shared file system for database or recovery file storage, refer to Configuring Storage for Oracle Database Files on a Supported Shared File System, and ensure that in addition to the volumes you create for Oracle Clusterware files, you also create additional volumes with sizes sufficient to store database files.
To use Automatic Storage Management for database or recovery file storage, refer to "Configuring Disks for Automatic Storage Management"
To use shared devices for database file storage, refer to "Configuring Storage for Oracle Database Files on Shared Storage Devices".
Note:If you choose to configure database files on raw devices, note that you must complete database software installation first, and then configure storage after installation.
You cannot use OUI to configure a database that uses raw devices for storage. In a future release, the option to use raw devices for database storage will become unavailable.
To check for all shared file systems available across all nodes on the cluster on a supported shared file system, log in as the installation owner user (
crs), and use the following syntax:
/mountpoint/runcluvfy.sh comp ssa -n node_list
If you want to check the shared accessibility of a specific shared storage type to specific nodes in your cluster, then use the following command syntax:
/mountpoint/runcluvfy.sh comp ssa -n node_list -s storageID_list
In the preceding syntax examples, the variable
mountpoint is the mountpoint path of the installation media, the variable
node_list is the list of nodes you want to check, separated by commas, and the variable
storageID_list is the list of storage device IDs for the storage devices managed by the file system type that you want to check.
For example, if you want to check the shared accessibility from
node2 of storage devices
/dev/sdc, and your mountpoint is
/dev/dvdrom/, then enter the following command:
$ /mnt/dvdrom/runcluvfy.sh comp ssa -n node1,node2 -s /dev/sdb,/dev/sdc
If you do not specify storage device IDs in the command, then the command searches for all available storage devices connected to the nodes on the list.
Database files consist of the files that make up the database, and the recovery area files. There are four options for storing database files:
Network File System (NFS)
Automatic Storage Management (ASM)
Raw devices (Database files only--not for the recovery area)
During configuration of Oracle Clusterware, if you selected NFS, and the volumes that you created are large enough to hold the database files and recovery files, then you have completed required preinstallation steps. You can proceed to Chapter 6, "Installing Oracle Clusterware".
If you want to place your database files on ASM, then proceed to Configuring Disks for Automatic Storage Management.
If you want to place your database files on raw devices, and manually provide storage management for your database and recovery files, then proceed to "Configuring Storage for Oracle Database Files on Shared Storage Devices".
Note:Databases can consist of a mixture of ASM files and non-ASM files. Refer to Oracle Database Administrator's Guide for additional information about ASM.
Review the following sections to complete storage requirements for Oracle Database files:
To use a file system for Oracle Database files, the file system must comply with the following requirements:
To use a cluster file system, it must be a supported cluster file system. Refer to OracleMetalink (
https://metalink.oracle.com) for a list of supported cluster file systems.
If you choose to place your database files on a shared file system, then one of the following must be true:
The file systems consist of at least two independent file systems, with the database files on one file system, and the recovery files on a different file system.
oracle user must have write permissions to create the files in the path that you specify.
Use Table 5-2 to determine the partition size for shared file systems.
|File Types Stored||Number of Volumes||Volume Size|
Oracle Database files
At least 1.5 GB for each volume
Note: Recovery files must be on a different volume than database files
At least 2 GB for each volume
In Table 5-2, the total required volume size is cumulative. For example, to store all database files on the shared file system, you should have at least 3.4 GB of storage available over a minimum of two volumes.
Network-attached storage (NAS) systems use NFS to access data. You can store data files on a supported NFS system.
NFS file systems must be mounted and available over NFS mounts before you start installation. Refer to your vendor documentation to complete NFS configuration and mounting.
This section contains the following information about Direct NFS:
With Oracle Database 11g release 1 (11.1), instead of using the operating system kernel NFS client, you can configure Oracle Database to access NFS V3 servers directly using an Oracle internal Direct NFS client.
To enable Oracle Database to use Direct NFS, the NFS file systems must be mounted and available over regular NFS mounts before you start installation. The mount options used in mounting the file systems are not relevant, as Direct NFS manages settings after installation. Refer to your vendor documentation to complete NFS configuration and mounting.
Some NFS file servers require NFS clients to connect using reserved ports. If your filer is running with reserved port checking, then you must disable it for Direct NFS to operate. To disable reserved port checking, consult your NFS file server documentation.
If you use Direct NFS, then you can choose to use a new file specific for Oracle datafile management,
oranfstab, to specify additional options specific for Oracle Database to Direct NFS. For example, you can use
oranfstab to specify additional paths for a mount point. You can add the
oranfstab file either to
/etc or to
oranfstab file is not required to use NFS or Direct NFS.
With Oracle RAC installations, if you want to use Direct NFS, then you must replicate the file
/etc/oranfstab on all nodes, and keep each
/etc/oranfstab file synchronized on all nodes.
oranfstab file is placed in
$ORACLE_HOME/dbs, the entries in the file are specific to a single database. In this case, all nodes running an Oracle RAC database use the same
oranfstab file is placed in
/etc, then it is globally available to all Oracle databases, and can contain mount points used by all Oracle databases running on nodes in the cluster, including single-instance databases. However, on Oracle RAC systems, if the
oranfstab file is placed in
/etc, then you must replicate the file
/etc/oranfstab file on all nodes, and keep each
/etc/oranfstab file synchronized on all nodes, just as you must with the
In all cases, mount points must be mounted by the kernel NFS system, even when they are being served using Direct NFS.
Direct NFS determines mount point settings to NFS storage devices based on the configurations in
/etc/mtab, which are changed with configuring the
Direct NFS searches for mount entries in the following order:
Direct NFS uses the first matching entry found.
Note:You can have only one active Direct NFS implementation for each instance. Using Direct NFS on an instance will prevent another Direct NFS implementation.
If Oracle Database uses Direct NFS mount points configured using
oranfstab, then it first verifies kernel NFS mounts by cross-checking entries in
oranfstab with operating system NFS mount points. If a mismatch exists, then Direct NFS logs an informational message, and does not serve the NFS server. If Oracle Database is unable to open an NFS server using Direct NFS, then Oracle Database uses the platform operating system kernel NFS client. In this case, the kernel NFS mount options must be set up as defined in "Checking NFS Mount and Buffer Size Parameters for Oracle RAC". Additionally, an informational message will be logged into the Oracle alert and trace files indicating that Direct NFS could not be established. The Oracle files resident on the NFS server that are served by the Direct NFS Client are also accessible through the operating system kernel NFS client. The usual considerations for maintaining integrity of the Oracle files apply in this situation.
Direct NFS can use up to four network paths defined in the
oranfstab file for an NFS server. The Direct NFS client performs load balancing across all specified paths. If a specified path fails, then Direct NFS reissues I/O commands over any remaining paths.
Use the following views for Direct NFS management:
v$dnfs_servers: Shows a table of servers accessed using Direct NFS.
v$dnfs_files: Shows a table of files currently open using Direct NFS.
v$dnfs_channels: Shows a table of open network paths (or channels) to servers for which Direct NFS is providing files.
v$dnfs_stats: Shows a table of performance statistics for Direct NFS.
Complete the following procedure to enable Direct NFS:
oranfstab file with the following attributes for each NFS server to be accessed using Direct NFS:
Server: The NFS server name.
Path: Up to four network paths to the NFS server, specified either by IP address, or by name, as displayed using the
Export: The exported path from the NFS server.
Mount: The local mount point for the NFS server.
Note:On Linux and UNIX platforms, the location of the
The following is an example of an
oranfstab file with two NFS server entries:
server: MyDataServer1 path: 126.96.36.199 path: 188.8.131.52 export: /vol/oradata1 mount: /mnt/oradata1 server: MyDataServer2 path: NfsPath1 path: NfsPath2 path: NfsPath3 path: NfsPath4 export: /vol/oradata2 mount: /mnt/oradata2 export: /vol/oradata3 mount: /mnt/oradata3 export: /vol/oradata4 mount: /mnt/oradata4 export: /vol/oradata5 mount: /mnt/oradata5
Oracle Database uses an ODM library,
libnfsodm10.so, to enable Direct NFS. To replace the standard ODM library,
$ORACLE_HOME/lib/libodm10.so, with the ODM NFS library,
libnfsodm10.so, complete the following steps:
Use one of the following methods to disable the Direct NFS client:
Restore the stub
libodm10.so file by reversing the process you completed in step 2b, "Enabling Direct NFS Client Oracle Disk Manager Control of NFS"
Remove the specific NFS server or export paths in the
Note:If you remove an NFS path that Oracle Database is using, then you must restart the database for the change to be effective.
If you are using Direct NFS, note that will not serve an NFS server with write size values (
wtmax) less than 32768.
/etc/fstab file on each node with an entry similar to the following:
nfs_server:/vol/DATA/oradata /u02/oradata nfs\ rw,bg,hard,nointr,rsize=32768,wsize=32768,tcp,noac,forcedirectio, vers=3, suid
Be aware that mount point requirements are different for binaries and Oracle Clusterware mount points.
Note:Refer to your storage vendor documentation for additional information about mount options.
Use the following instructions to create directories for shared file systems for Oracle Database and recovery files (for example, for a RAC database).
If necessary, configure the shared file systems that you want to use and mount them on each node.
Note:The mount point that you use for the file system must be identical on each node. Ensure that the file systems are configured to mount automatically when a node restarts.
df -h command to determine the free disk space on each mounted file system.
From the display, identify the file systems that you want to use:
|File Type||File System Requirements|
|Database files||Choose either:
|Recovery files||Choose a file system with at least 2 GB of free disk space.|
If you are using the same file system for more than one type of file, then add the disk space requirements for each type to determine the total disk space requirement.
Note the names of the mount point directories for the file systems that you identified.
If the user performing installation (typically,
oracle) has permissions to create directories on the disks where you plan to install Oracle Database, then DBCA creates the Oracle Database file directory, and the Recovery file directory.
If the user performing installation does not have write access, then you must create these directories manually using commands similar to the following to create the recommended subdirectories in each of the mount point directories and set the appropriate owner, group, and permissions on them:
Database file directory:
# mkdir /mount_point/oradata # chown oracle:oinstall /mount_point/oradata # chmod 775 /mount_point/oradata
Recovery file directory (Fast recovery area):
# mkdir /mount_point/Fast_recovery_area # chown oracle:oinstall /mount_point/Fast_recovery_area # chmod 775 /mount_point/Fast_recovery_area
When you have completed creating subdirectories in each of the mount point directories, and set the appropriate owner, group, and permissions, you have completed NFS configuration for Oracle Database shared storage.
This section describes how to configure disks for use with Automatic Storage Management. Before you configure the disks, you must determine the number of disks and the amount of free disk space that you require. The following sections describe how to identify the requirements and configure the disks:
Note:For Automatic Storage Management installations:
Although this section refers to disks, you can also use zero-padded files on a certified NAS storage device in an Automatic Storage Management disk group. Refer to Oracle Database Installation Guide for Solaris Operating System (SPARC 64-Bit) for information about creating and configuring NAS-based files for use in an Automatic Storage Management disk group.
To identify the storage requirements for using Automatic Storage Management, you must determine how many devices and the amount of free disk space that you require. To complete this task, follow these steps:
Determine whether you want to use Automatic Storage Management for Oracle Database files, recovery files, or both.
Note:You do not have to use the same storage mechanism for database files and recovery files. You can use the file system for one file type and Automatic Storage Management for the other.
If you choose to enable automated backups and you do not have a shared file system available, then you must choose Automatic Storage Management for recovery file storage.
If you enable automated backups during the installation, you can choose Automatic Storage Management as the storage mechanism for recovery files by specifying an Automatic Storage Management disk group for the Fast recovery area. Depending on how you choose to create a database during the installation, you have the following options:
If you select an installation method that runs Database Configuration Assistant in interactive mode (for example, by choosing the Advanced database configuration option) then you can decide whether you want to use the same Automatic Storage Management disk group for database files and recovery files, or use different disk groups for each file type.
The same choice is available to you if you use Database Configuration Assistant after the installation to create a database.
If you select an installation method that runs Database Configuration Assistant in noninteractive mode, then you must use the same Automatic Storage Management disk group for database files and recovery files.
The redundancy level that you choose for the Automatic Storage Management disk group determines how Automatic Storage Management mirrors files in the disk group and determines the number of disks and amount of free disk space that you require, as follows:
An external redundancy disk group requires a minimum of one disk device. The effective disk space in an external redundancy disk group is the sum of the disk space in all of its devices.
Because Automatic Storage Management does not mirror data in an external redundancy disk group, Oracle recommends that you select external redundancy only use only RAID or similar devices that provide their own data protection mechanisms for disk devices.
In a normal redundancy disk group, to increase performance and reliability, Automatic Storage Management by default uses two-way mirroring. A normal redundancy disk group requires a minimum of two disk devices (or two failure groups). The effective disk space in a normal redundancy disk group is half the sum of the disk space in all of its devices.
For most installations, Oracle recommends that you select normal redundancy disk groups.
In a high redundancy disk group, Automatic Storage Management uses three-way mirroring to increase performance and provide the highest level of reliability. A high redundancy disk group requires a minimum of three disk devices (or three failure groups). The effective disk space in a high redundancy disk group is one-third the sum of the disk space in all of its devices.
While high redundancy disk groups do provide a high level of data protection, you should consider the greater cost of additional storage devices before deciding to select high redundancy disk groups.
|Redundancy Level||Minimum Number of Disks||Database Files||Recovery Files||Both File Types|
|External||1||1.15 GB||2.3 GB||3.45 GB|
|Normal||2||2.3 GB||4.6 GB||6.9 GB|
|High||3||3.45 GB||6.9 GB||10.35 GB|
For Oracle RAC installations, you must also add additional disk space for the Automatic Storage Management metadata. You can use the following formula to calculate the additional disk space requirements (in MB):
15 + (2 * number_of_disks) + (126 * number_of_Automatic_Storage_Management_instances)
For example, for a four-node Oracle RAC installation, using three disks in a high redundancy disk group, you require an additional 525 MB of disk space:
15 + (2 * 3) + (126 * 4) = 525
If an Automatic Storage Management instance is already running on the system, then you can use an existing disk group to meet these storage requirements. If necessary, you can add disks to an existing disk group during the installation.
The following section describes how to identify existing disk groups and determine the free disk space that they contain.
Note:Complete this step only if you intend to use an installation method that runs Database Configuration Assistant in interactive mode, for example, if you intend to choose the Custom installation type or the Advanced database configuration option. Other installation types do not enable you to specify failure groups.
If you intend to use a normal or high redundancy disk group, then you can further protect your database against hardware failure by associating a set of disk devices in a custom failure group. By default, each device comprises its own failure group. However, if two disk devices in a normal redundancy disk group are attached to the same SCSI controller, then the disk group becomes unavailable if the controller fails. The controller in this example is a single point of failure.
To protect against failures of this type, you could use two SCSI controllers, each with two disks, and define a failure group for the disks attached to each controller. This configuration would enable the disk group to tolerate the failure of one SCSI controller.
Note:If you define custom failure groups, then you must specify a minimum of two failure groups for normal redundancy disk groups and three failure groups for high redundancy disk groups.
If you are sure that a suitable disk group does not exist on the system, then install or identify appropriate disk devices to add to a new disk group. Use the following guidelines when identifying appropriate disk devices:
All of the devices in an Automatic Storage Management disk group should be the same size and have the same performance characteristics.
Do not specify more than one partition on a single physical disk as a disk group device. Automatic Storage Management expects each disk group device to be on a separate physical disk.
Although you can specify a logical volume as a device in an Automatic Storage Management disk group, Oracle does not recommend their use. Logical volume managers can hide the physical disk architecture, preventing Automatic Storage Management from optimizing I/O across the physical devices. They are not supported with Oracle RAC.
If you want to store either database or recovery files in an existing Automatic Storage Management disk group, then you have the following choices, depending on the installation method that you select:
If you select an installation method that runs Database Configuration Assistant in interactive mode (for example, by choosing the Advanced database configuration option), then you can decide whether you want to create a disk group, or to use an existing one.
The same choice is available to you if you use Database Configuration Assistant after the installation to create a database.
If you select an installation method that runs Database Configuration Assistant in noninteractive mode, then you must choose an existing disk group for the new database; you cannot create a disk group. However, you can add disk devices to an existing disk group if it has insufficient free space for your requirements.
Note:The Automatic Storage Management instance that manages the existing disk group can be running in a different Oracle home directory.
To determine if an existing Automatic Storage Management disk group exists, or to determine if there is sufficient disk space in a disk group, you can use Oracle Enterprise Manager Grid Control or Database Control. Alternatively, you can use the following procedure:
View the contents of the
oratab file to determine if an Automatic Storage Management instance is configured on the system:
$ more /etc/oratab
If an Automatic Storage Management instance is configured on the system, then the
oratab file should contain a line similar to the following:
In this example,
+ASM2 is the system identifier (SID) of the Automatic Storage Management instance, with the node number appended, and
oracle_home_path is the Oracle home directory where it is installed. By convention, the SID for an Automatic Storage Management instance begins with a plus sign.
ORACLE_HOME environment variables to specify the appropriate values for the Automatic Storage Management instance that you want to use.
Connect to the Automatic Storage Management instance as the
SYS user with
SYSDBA privilege and start the instance if necessary:
$ $ORACLE_HOME/bin/sqlplus "SYS/SYS_password as SYSDBA" SQL> STARTUP
Enter the following command to view the existing disk groups, their redundancy level, and the amount of free disk space in each one:
SQL> SELECT NAME,TYPE,TOTAL_MB,FREE_MB FROM V$ASM_DISKGROUP;
From the output, identify a disk group with the appropriate redundancy level and note the free space that it contains.
If necessary, install or identify the additional disk devices required to meet the storage requirements listed in the previous section.
Note:If you are adding devices to an existing disk group, then Oracle recommends that you use devices that have the same size and performance characteristics as the existing devices in that disk group.
The following subsections describe how to configure Oracle Clusterware files on raw devices.
Before installing the Oracle Database 11g release 1 (11.1) software with Oracle RAC, create enough partitions of specific sizes to support your database, and also leave a few spare partitions of the same size for future expansion. For example, if you have space on your shared disk array, then select a limited set of standard partition sizes for your entire database. Partition sizes of 50 MB, 100 MB, 500 MB, and 1 GB are suitable for most databases. Also, create a few very small and a few very large spare partitions that are (for example) 1 MB and perhaps 5 GB or greater in size. Based on your plans for using each partition, determine the placement of these spare partitions by combining different sizes on one disk, or by segmenting each disk into same-sized partitions.
Note:Be aware that each instance has its own redo log files, but all instances in a cluster share the control files and data files. In addition, each instance's online redo log files must be readable by all other instances to enable recovery.
In addition to the minimum required number of partitions, you should configure spare partitions. Doing this enables you to perform emergency file relocations or additions if a tablespace data file becomes full.
Note:For new installations, Oracle recommends that you do not use raw devices for database files.
Table 5-3 lists the number and size of the shared partitions that you must configure for database files.
|Number||Partition Size (MB)||Purpose|
400 + (Number of instances * 250)
Number of instances
2 * number of instances
Note:If you prefer to use manual undo management, instead of automatic undo management, then, instead of the
nshared storage devices, you must create a single rollback segment tablespace (RBS) on a shared storage device partition that is at least 500 MB in size.
If you intend to use IDE or SCSI devices for the raw devices, then follow these steps:
If necessary, install or configure the shared disk devices that you intend to use for the raw devices and restart the system.
Note:Because the number of partitions that you can create on a single device is limited, you might need to create the required partitions on more than one device.
# /sbin/fdisk -l
|Disk Type||Device Name Format||Description|
|In this example,
|In this example,
You can create the required partitions either on new devices that you added or on previously partitioned devices that have unpartitioned free space. To identify devices that have unpartitioned free space, examine the start and end cylinder numbers of the existing partitions and determine whether the device contains unused cylinders.
# /sbin/fdisk devicename
When creating partitions:
p command to list the partition table of the device.
n command to create a partition.
After you have created the required partitions on this device, use the
w command to write the modified partition table to the device.
Refer to the
fdisk man page for more information about creating partitions.
With the release of Oracle Database 11g and Oracle RAC release 11g, configuring raw devices using Database Configuration Assistant is not supported.
oracle user, use the following command syntax to start Cluster Verification Utility (CVU) stage verification to check hardware, operating system, and storage setup:
/mountpoint/runcluvfy.sh stage –post hwos –n node_list [-verbose]
In the preceding syntax example, replace the variable
node_list with the names of the nodes in your cluster, separated by commas. For example, to check the hardware and operating system of a two-node cluster with nodes
node2, with the mountpoint
/mnt/dvdrom/ and with the option to limit the output to the test results, enter the following command:
$ /mnt/dvdrom/runcluvfy.sh stage –post hwos –n node1,node2
Select the option
-verbose to receive detailed reports of the test results, and progress updates about the system checks performed by Cluster Verification Utility.