[Translated from mos] Use asm to deploy ultra-large databases (10 TB to PB)-for oracle 10 GB and asm10tb

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[Translated from mos] Use asm to deploy ultra-large databases (10 TB to PB)-for oracle 10 GB and asm10tb


Use asm to deploy super-large databases (10 TB to PB)

Reference Original:
Deployment of very large databases (10 TB to PB range) with Automatic Storage Management (ASM) (Doc ID 368055.1)


Range:
This article applies to the asm configuration on all platforms, including the use of rac and single-instance environments.
This article applies to the creation of super large databases, and the database will grow to more than 10 TB.


Challenges:
Asm metadata Storage

Solution:

Au (Allocation unit) is the basic allocation unit in the asm disk group. By default, the size of asm au is set to 1 MB.

Asm data extents bare device, which stores the content of the asm file.
In oracle database 10 Gb, each data extent is a separate au (Allocation Unit)
Because of the 1-to-1 exting (map) Relationship between extent and au, an asm file extent map can be increased to GB in a large database. In this case, the memory usage and file opening performance are inefficient.

Asm provides two implicit parameters that allow you to create an asm disk with a size of 16 MB and a fine grain striping size of 1 MB (previously KB ).
This reduces the extent map size to the original 1/16. au parameter, which can only be used when the disk group is created. When a disk group is created, you cannot change the au size of the disk group.

To change the au size (that is, the data extent size), you must reset the following asm implicit parameter: change from 1 MB to 16 MB, and change fine grain stripe size to 1 MB.
The asm instance must be closed, and _ asm_ausize and _ asm_stripesize must be in the init. the ora parameter file is reset (reset), and then the asm instance is restarted to inherit the new value of this parameter.
O _ asm_ausize = 16777216
O _ asm_stripesize = 1048576
---> Note: the unit of the preceding values is Byte.

You must modify the asm file template and set stripe type to 'fine 'for all file types to use 1 MB striping.
This must be done after the asm diskgoup is created.


To make these two parameter values take effect, the asm instance must be restarted.

After these two implicit parameters are set and the asm instance is restarted, any created asm disk will use the new au size and FINE stripe size.

To use the normal 1 MB au size and 128 k fine stripe size when creating an asm disk group, these two implicit parameters should be removed and the asm needs to be restarted.


Example:
In the following example, an asm disk with a size of 16 MB (data extents size) is created. For all datafiles, the FINE striping size is 1 MB.

1. Close the asm instance

2. Add the following parameters to the init. ora file of asm:
_ Asm_ausize = 16777216
_ Asm_stripesize = 1048576
3. Restart the asm instance.

4. Create a disk group:
Create diskgroup diskgroup_name disk '/devices/diska1', '/devices/diska2 ';

5. Change the all asm file template to FINE grained:
O alter diskgroup diskgroup_name alter template <tmpl> ATTRIBUTES (FINE );
O Repeat this command for all ASM file types. Attributes types are listed
Below:
O CONTROLFILE, DATAFILE, ONLINELOG, ARCHIVELOG, TEMPFILE, BACKUPSET,
PARAMETERFILE, DATAGUARDCONFIG, FLASHBACK, CHANGETRACKING, DUMPSET,
XTRANSPORT, AUTOBACKUP


16 MB ausize and 1 mb fine grain striping can effectively provide 1 mb data striping, while reducing the overload of the asm file extent.
This configuration is faster when you open the asm file, and more effectively supports the asm database within the range of 10 TB to PB.

Note:
Apply the fix for Bug 5100163 in 10.2.0.4

This patch shoshould be applied if you have created ASM Diskgroups with the AU size greater than 1 MB and have fewer than 3585 user files.
The following command must be ran on each Diskgroup after applying the patch:
Alter diskgroup <DG_NAME> CHECK ALL REPAIR


 




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