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Microsoft PowerPoint - lesson_10_5day.ppt [Compatibility Mode]

http://dc161.4shared.com/doc/3AH6UxPV/preview.html

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Microsoft PowerPoint - lesson_10_5day.ppt [Compatibility Mode]

http://dc161.4shared.com/doc/3AH6UxPV/preview.html

Oracle 11g: RAC and Grid Infrastructure Administration Accelerated

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ASM Files and Volumes The Automatic Storage Management (ASM) feature of Oracle database has been extended in Oracle Grid Infrastructure 11g Release 2 to include support for a general purpose cluster le system, the ASM Cluster File System (ACFS). To understand the operation of this feature, some terminology needs to be dened and explained. At the operating system (OS) level, the ASM instance provides the disk group, which is a logical container for physical disk space. The disk group can hold ASM database les and ASM dynamic volume les. The ASM Dynamic Volume Manager (ADVM) presents the volume device le to the operating system as a block device. The mkfs utility can be used to create an ASM le system in the volume device le. Four OS kernel modules loaded in the OS provide the data service. On Linux, they are: , the ASM module; oracleadvm, the ASM dynamic volume manager module; oracleasm oracleoks , the kernel services module; and oracleacfs, the ASM le system module. These modules provide the ASM Cluster File System, ACFS snapshots, the ADVM, and cluster services. The ASM volumes are presented to the OS as a device le at /dev/asm/ . The volume device le appears as another ASM le to the ASM Instance and asmcmd utility. The ASM layers are transparent to the OS le system commands. Only the les and directories created in ACFS and the ACFS snapshots are visible to the OS le system commands. Other le system types such as ext3 and NTFS may be created in an ADMV volume using the mkfs command on Linux and advmutil commands on Windows. Oracle 11g: RAC and Grid Infrastructure Administration Accelerated 10 - 3

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ACFS and ADVM Architecture Overview In 10g, Automatic Storage Management (ASM) is both a le system and volume manager built specically for Oracle database les. Oracle 11g Release 2 includes the ASM dynamic volume manager (ADVM) and Oracle ASM cluster le system (ACFS). ADVM provides volume management services and a standard disk device driver interface to clients. Clients, such as le 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 le. The administrator can use the ADVM to create volumes that contain le systems. These le systems can be used to support les beyond Oracle database les such as executables, report les, trace les, alert logs, and other application data les. With the addition of ADVM and ACFS, ASM becomes a complete storage solution of user data for both database and non-database le needs. ACFS is intended as a general le system accessible by the standard OS utilities. ACFS can be used in either a single server or a cluster environment. Note: Oracle ACFS le 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 le systems cannot be used for an OS root directory or boot directory.

Oracle 11g: RAC and Grid Infrastructure Administration Accelerated

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ACFS and ADVM Architecture Overview (continued) 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 congured into the operating system. A volume device is constructed from an ASM le. ASM le extents map the ASM volume le to logical blocks located on specic 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 le. An ASM volume is an ASM le. It inherits the properties of the ASM disk group and behaves similar to any other ASM le. ASM volume storage is automatically rebalanced whenever a storage conguration change occurs. This reconguration 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 le is created automatically when an ASM volume is created using either SQL*Plus, ASMCA, or the Enterprise Manager graphical interfaces. On Linux, this device le is directory. You can congure both disk group mount and volume enable created in the /dev/asm operations to occur automatically upon ASM instance startup. The volume device le 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, , and oracleadvm). The ASM instance is started by the ASM cluster registry service oracleoks (CRS) agent, which will also mount the appropriate ASM disk groups and enable volumes. The CRS agent will then mount any ACFS le systems in the Oracle Cluster Registry (OCR). Similar actions are performed on Windows. ACFS le systems are accessed through OS le system tools and APIs on UNIX and Linux systems, and accessed through Windows le system tools and APIs on Windows systems. Remote access is supported using standard NAS le access protocols such as network le systems (NFS) and common internet le system (CIFS) in support of heterogeneous le 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 conguration and loading of the ACFS drivers is performed by the root scripts associated with the Oracle Grid Infrastructure installation. ACFS le 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.asmcmd ,

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ADVM Processes A small number of processes will be added to the ASM instance when a volume is enabled. These processes are not started when there are no volumes congured. The Volume Driver Background (VDBG) process forwards ASM requests to lock or unlock an extent for rebalancing, resize the volume, ofine the disk, add or drop a disk, and force and dismount a disk group to the dynamic volume manager driver. The VDBG is a fatal background process so the unplanned death of this process brings down the ASM instance. Volume Background (VBGn) processes wait for requests from the dynamic volume manager driver that need to be coordinated with the ASM instance. An example of such a request would be opening or closing an ASM volume le when the dynamic volume manager driver receives an open for a volume (possibly due to a le system mount request) or close for an open volume (possibly due to a le system unmount request). The unplanned death of any of these processes does not have an effect on the ASM instance. Volume Membership Background (VMB) coordinates cluster membership with the ASM instance.

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ADVM Restrictions Although ADVM provides a standard disk device interface for dynamic volumes, the following restrictions should be noted: Device partitions are not supported on Oracle ADVM dynamic volumes. Dynamic volumes supersede traditional device partitioning. Each volume is individually named and may be congured for a single le system. Oracle ADVM volumes may be created on demand from ASM disk group storage and dynamically resized as required. These attributes make Oracle ADVM volumes far more exible than physical devices and associated partitioning schemes. On Linux platforms, Oracle ADVM volume devices are created as block devices regardless of the conguration of the storage underpinning the ASM disk group. Do not use the raw command to map Oracle ADVM volume block devices into raw volume devices. You should not create multipath devices over Oracle A