Explore Oracle ASM

Explore Oracle's ASM01. Now let's talk about how to install ASM. The installation of ASM must be based on the installed operating system and database software and instances.

Explore Oracle's ASM01. Now let's talk about how to install ASM. The installation of ASM must be based on the installed operating system and database software and instances.

I, ASM(Automatic Storage Management) reason:

ASMYesOracle 10g R2To simplifyOracleA new feature introduced by database management, which isOracleThe volume manager provided by Alibaba Cloud is mainly used to replace the volume manager provided by the operating system.LVMIt not only supports a single instance, but alsoRACThe support is also very good.ASMYou can automatically manage disk groups and provide effective data redundancy. UseASM(Automatic Storage Management), the database administrator no longer needsORACLEWhich simplifies the management and classification of thousands of data files.DBACan greatly improve the work efficiency.

II,What isASM

ASMIt provides platform-independent file systems, logical volume management, and softwareRAIDService.ASMSupports striping and Disk Images, enabling you to add or remove disks and automatically balance them when the database is loaded.I/OTo delete the "Hotspot ". It also supports direct and asynchronousI/OAnd useOracle9iIntroduced inOracleData ManagerAPI(SimplifiedI/OSystem Call interface ).

ASMIs used as a separateOracleInstance implementation and deployment, and it only needs to have a parameter file, without any other physical files, you can startASMInstance. Only when it is running can it be accessed by other data. InLinuxOn the platform, only the runningOCSSDService (OracleThe installer is installed by default .)ASM.

III,UseASMBenefits:

1,SetI/OEvenly distributed to all available disk drives to prevent hot spots and maximize performance.

2,The configuration is simpler, and it maximizes the utilization of storage resources that promote database merging.

3,Internal Support for large files

4,Perform automatic contact redistribution after the storage capacity is added or deleted in increments.

5,Maintain redundant copies of data to improve availability.

6,Supported10g,11gData storage andRACShared storage management

7,Support third-party multi-path Software

8,UseOMFFile Management

IV, ASMRedundancy:

ASMUse the unique image algorithm:It is not an image disk, but an image disk.. As a result, in order to provide continuous protection when a fault occurs, you only need the space capacity in the disk group, instead of preparing a hot backup.(Hot spare)Disk. It is not recommended that you create fault groups of different sizes, because this will cause problems when allocating secondary disk areas.ASMWhen the primary disk of a file is assigned to a disk in the disk group, it allocates an image copy of the disk area to another disk in the disk group. The primary disk on a given disk has its own mirror disk on a partner disk in the disk group.ASMMake sure that the primary disk and its image copy do not reside in the same fault group. The redundancy of a disk can take the following form: two-way Image File(At least two fault groups are required)Common Redundancy(Default Redundancy)And use a three-way image(At least3Fault groups)Provides high redundancy with a high degree of protection.Once a disk group is created, its redundancy level cannot be changed.To change the redundancy of a disk group, you must create another disk group with proper redundancy and then useRMANRestore orDBMS_FILE_TRANSFERMove the data file to the newly created disk group.

Three different redundancy methods are as follows:

Technology; valid disk space is the sum of the space of all disk devices.

Images to protect data,Valid disk space is the sum of the size of all disk devices1/2(Most used)

Images to protect data,To improve performance and data security, at least three Disks (threeFailure group); Valid disk space is the sum of all disk devices1/3Although the redundancy level is high, the hardware cost is also the highest.

V, ASMProcess

ASMIn addition to the traditionalDBWR, LGWR, CKPT, SMON, PMONAnd other processes include the following four new background processes:

RBAL:Coordinates disk rebalancing activities(Responsible for disk group balancing)

ARB0-ARBn:Many such processes can exist at the same time.ARB0,ARB1, And so on, execute the actual rebalancing of the allocation unit moving process.

GMON:UsedASMDisk group monitoring

ASMBAndASMThe front-end process connection of the Instance periodically checks twoInstance. Each database instance can be associated with only oneASMInstance connection, so the database only has oneASMBBackground process. If a node has multiple database instances, they can only share oneASMInstance.

RBALUsed for global calling to open a disk in a disk group.ASMBProcess and the node'sCSSThe daemon processes communicate with each other and receive messages fromASMThe file interval ing information of the instance.ASMBAlso responsibleASMInstance provisionI/OStatistical data

CSSCluster synchronization service. To useASM, Make sure that you have runCSSCluster synchronization service,CSSResponsibleASMSynchronization between instances and database instances.

VI, ASMSupportedDatafile,Logfiles,Control files,Archivelogs,RMAN backup setsAnd other automaticDatabaseFileManagement

VII, ASMMappings between instances and database instances

8, Cluster ASMArchitecture

First Release):

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