In 10g, Automatic Storage Management (ASM) is both a file system and volume manager built specifically for Oracle database files.
Oracle 11g Release 2 includes the ASM dynamic volume manager (ADVM) and Oracle ASM cluster file system (ACFS).
ADVM provides volume management services and a standard disk device driver interface to clients. Clients, such as file systems and other disk-based applications, issue I/O requests to ADVM volume devices as they would to other storage devices on a vendor operating system.
ADVM extends ASM by providing a disk driver interface to storage backed by an ASM file. The administrator can use the ADVM to create volumes that contain file systems. These file systems can be used to support files beyond Oracle database files such as executables, report files, trace files, alert logs, and other application data files.
With the addition of ADVM and ACFS, ASM becomes a complete storage solution of user data for both database and non-database file needs. ACFS is intended as a general file system accessible by the standard OS utilities. ACFS can be used in either a single server or a cluster environment.
Note: Oracle ACFS file systems cannot be used for an Oracle base directory or an Oracle grid infrastructure home that contains the software for Oracle Clusterware, ASM, Oracle ACFS, and Oracle ADVM components. Oracle ACFS file systems cannot be used for an OS root directory or boot directory.
ASM volumes serve as containers for storage presented as a block device accessed through ADVM. File systems or user processes can do I/O on this “ASM volume device” just as they would on any other device. To accomplish this, ADVM is configured into the operating system.
A volume device is constructed from an ASM file. ASM file extents map the ASM volume file to logical blocks located on specific physical devices. Additional processes are started as part of the ASM instance and serve as intermediaries between the ASM instance and ADVM. To use the ADVM driver, an ASM instance must exist with at least one disk group mounted that can be used to contain an ASM volume file.
An ASM volume is an ASM file. It inherits the properties of the ASM disk group and behaves similar to any other ASM file. ASM volume storage is automatically rebalanced whenever a storage configuration change occurs. This reconfiguration can be performed while an ASM volume is in use. Because ASM uses direct I/O, ASM volumes offer performance equivalent to raw disks.
An OS device file is created automatically when an ASM volume is created using either asmcmd, SQL*Plus, ASMCA, or the Enterprise Manager graphical interfaces. On Linux, this device file is created in the /dev/asm directory. You can configure both disk group mount and volume-enable operations to occur automatically upon ASM instance startup. The volume device file names are unique clusterwide and persistent across all nodes in the cluster that have an ASM instance running with the disk group mounted and volumes enabled.
Upon Linux system startup, the Oracle clusterware startup will load the drivers (oraclesacfs, oracleoks, and oracleadvm). The ASM instance is started by the ASM cluster registry service (CRS) agent, which will also mount the appropriate ASM disk groups and enable volumes. The CRS agent will then mount any ACFS file systems in the Oracle Cluster Registry (OCR).
Similar actions are performed on Windows.
ACFS file systems are accessed through OS file system tools and APIs on UNIX and Linux systems, and accessed through Windows file system tools and APIs on Windows systems. Remote access is supported using standard NAS file access protocols such as network file systems (NFS) and common Internet file system (CIFS) in support of heterogeneous file data sharing.
The ACFS File System and ADVM components are installed onto each host along with the other ASM components into the Grid Infrastructure home location. The ACFS components consist of drivers that are dynamically loadable OS modules, several command-line tools, and a set of processes that execute within the ASM instance. However, loading the ACFS drivers requires root privileges on UNIX/Linux and Administrator privileges on Windows. So, the configuration and loading of the ACFS drivers is performed by the root scripts associated with the Oracle Grid Infrastructure installation.
ACFS file systems are generally mounted on all cluster synchronization service (CSS) cluster members. In the event of a member failure, another cluster member will recover any outstanding metadata transactions on behalf of the failed member. In addition, any lock tokens held by the failed cluster members will be recovered and the failed member will be I/O fenced from the active CSS cluster. Following recovery, access by other active cluster members and any remote client systems may resume.
Oracle 11g Release 2 includes the ASM dynamic volume manager (ADVM) and Oracle ASM cluster file system (ACFS).
ADVM provides volume management services and a standard disk device driver interface to clients. Clients, such as file systems and other disk-based applications, issue I/O requests to ADVM volume devices as they would to other storage devices on a vendor operating system.
ADVM extends ASM by providing a disk driver interface to storage backed by an ASM file. The administrator can use the ADVM to create volumes that contain file systems. These file systems can be used to support files beyond Oracle database files such as executables, report files, trace files, alert logs, and other application data files.
With the addition of ADVM and ACFS, ASM becomes a complete storage solution of user data for both database and non-database file needs. ACFS is intended as a general file system accessible by the standard OS utilities. ACFS can be used in either a single server or a cluster environment.
Note: Oracle ACFS file systems cannot be used for an Oracle base directory or an Oracle grid infrastructure home that contains the software for Oracle Clusterware, ASM, Oracle ACFS, and Oracle ADVM components. Oracle ACFS file systems cannot be used for an OS root directory or boot directory.
ASM volumes serve as containers for storage presented as a block device accessed through ADVM. File systems or user processes can do I/O on this “ASM volume device” just as they would on any other device. To accomplish this, ADVM is configured into the operating system.
A volume device is constructed from an ASM file. ASM file extents map the ASM volume file to logical blocks located on specific physical devices. Additional processes are started as part of the ASM instance and serve as intermediaries between the ASM instance and ADVM. To use the ADVM driver, an ASM instance must exist with at least one disk group mounted that can be used to contain an ASM volume file.
An ASM volume is an ASM file. It inherits the properties of the ASM disk group and behaves similar to any other ASM file. ASM volume storage is automatically rebalanced whenever a storage configuration change occurs. This reconfiguration can be performed while an ASM volume is in use. Because ASM uses direct I/O, ASM volumes offer performance equivalent to raw disks.
An OS device file is created automatically when an ASM volume is created using either asmcmd, SQL*Plus, ASMCA, or the Enterprise Manager graphical interfaces. On Linux, this device file is created in the /dev/asm directory. You can configure both disk group mount and volume-enable operations to occur automatically upon ASM instance startup. The volume device file names are unique clusterwide and persistent across all nodes in the cluster that have an ASM instance running with the disk group mounted and volumes enabled.
Upon Linux system startup, the Oracle clusterware startup will load the drivers (oraclesacfs, oracleoks, and oracleadvm). The ASM instance is started by the ASM cluster registry service (CRS) agent, which will also mount the appropriate ASM disk groups and enable volumes. The CRS agent will then mount any ACFS file systems in the Oracle Cluster Registry (OCR).
Similar actions are performed on Windows.
ACFS file systems are accessed through OS file system tools and APIs on UNIX and Linux systems, and accessed through Windows file system tools and APIs on Windows systems. Remote access is supported using standard NAS file access protocols such as network file systems (NFS) and common Internet file system (CIFS) in support of heterogeneous file data sharing.
The ACFS File System and ADVM components are installed onto each host along with the other ASM components into the Grid Infrastructure home location. The ACFS components consist of drivers that are dynamically loadable OS modules, several command-line tools, and a set of processes that execute within the ASM instance. However, loading the ACFS drivers requires root privileges on UNIX/Linux and Administrator privileges on Windows. So, the configuration and loading of the ACFS drivers is performed by the root scripts associated with the Oracle Grid Infrastructure installation.
ACFS file systems are generally mounted on all cluster synchronization service (CSS) cluster members. In the event of a member failure, another cluster member will recover any outstanding metadata transactions on behalf of the failed member. In addition, any lock tokens held by the failed cluster members will be recovered and the failed member will be I/O fenced from the active CSS cluster. Following recovery, access by other active cluster members and any remote client systems may resume.
No comments:
Post a Comment