11G New Features

Active database Duplication using RMAN

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Starting from 11g database can be duplicated with having prior copy of the database backup on the destination. Prior to 11g it requires source database, a copy of a backup on destination and destination db.

Beginning with 11g you can use the RMAN or Enterprise manager to create a duplicate database online. This feature instructs the source database to perform online image copies and archived log copies directly to the target instance. Preexisting backups are not required.

RMAN > DUPLICATE TARGET DATABASE
TO db_duplicate
FROM ACTIVE DATABASE
SPFILE PARAMETER_VALUE_CONVERT ‘/u02′, ‘u03′
SET SGA_MAX_SIXE = ‘500m’
SET SGA_TARGET = ‘250M’
SET LOG FILE_NAME_CONVERT = ‘/u02′, ‘u03′
DB_FILE_NAME_CONVERT = ‘/u02′, ‘u03′;

Using above command the target database is duplicated to database “db_duplicate” and the database file locations are changes from /u02 to /u03. Make sure that the /u03 partition is already existing on the OS side.

ASM Fast Mirror Resync

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- In 10g ASm assumes that an offline disk only contains stale data and reads no data from such disks as a result disk is put offline. After this ASM drops the disk from group and recreates all the extents using the mirror copy which is fairly time consuming process and may take hours.
- ASM fast mirror resync significantly reduces the time required to resync a transient failure of any disk. With this feature when disk goes offline ASM track all the changes to the extents during the offline time and when the disk comes online ASM quickly resync ONLY the extents that were affected during the offline period.

- DISK_REPAIR_TIME is the attribute that needs to be set corresponding to the disk group> This determines the duration of disk outage that ASM instance will tolerate being able to resync.

How to setup ASM fast mirror resync:

1. Use ALTER DISKGROUP to set the DISK_REPAIR_TIME attribute.

ALTER DISKGROUP diskgrp1 SET ATTRIBUTE ‘disk_repair_time’ = ‘3.5h’
or
ALTER DISKGROUP dg01 SET ATTRIBUTE ‘disk_repair_time’ = ‘210m’

2. Use ALTER DISKGROUP DISK ONLINE statement to bring the disk online.

For Example.

ALTER DISKGROUP diskgrp1 OFFLINE DISK diskgrp_1 DROP AFTER 10m;

This will take disk diskgrp_1 offline and drops it after 10 minutes.

3. Can refer to V$ASM_OPERATION view while running any of ALTER DISKGROUP commands as it displays name and current state of operation you are performing.

ASM Scalability

- 63 Disk groups
- 10,000 ASM Disks
- 4 Petabytes per ASM disk
- 40 Exabytes of storage
- 1 Million files per disk group
- Maximum filesize
External reduntancy : 140 PB
Nornal reduntancy : 42 PB
High reduntancy : 15 PB