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12c Database : ASM Enhancements : New Failgroup Repair Time

When an transient disk failures happens the time to take to repair the offline disk from mirror groups will be set by diskgroup_repair_time.

For example, If diskgroup_repair_time is set as 3 hours and with in this period if disk repair is not completed, the ASM will drop the disks.

ASM keeps track of the changed […]

12c Database : ASM Enhancements : Increased storage limits

Just to make a note here, (From Jafar notes)

The ASM storage hard limits on maximum ASM disk groups and disk size has been drastically increased.

In 12cR1, ASM support 511 ASM disk groups against 63 ASM disk groups in 11gR2.

Also, an ASM disk can be now 32PB size against 20PB in 11gR2.


12c Database : ASM Enhancements : OCR backup to disk group

Oracle Cluster Registry (OCR) backup in ASM disk group

Before to 12c the ocr backup is located in the master node local disk at GRID_HOME/cdata/backup, but if OCR is corrupted and you have to restore you will need to find the master node and initiate the restore option.

Storing the OCR backup in an […]

12c Database : ASM Enhancements : Password files in ASM Disk group

ASM version 11.2 allowed ASM spfile to be placed in a disk group.

In 12c we can also put ASM password file in an ASM disk group.

Unlike ASM spfile, the access to the ASM password file is possible only after ASM startup and once the disk group containing the password is mounted. […]

12c Database : ASM Enhancements : Logical corruption checks on disk, disk scrubbing

ASM 12c provides proactive scrubbing capabilities on disks that check for logical corruptions and automatically repair them where possible. 

SQL> alter diskgroup DG1 scrub repair; Diskgroup altered.

SQL> alter diskgroup DG1 scrub file ‘+DATA_DISK/Geek DBA12C/DATAFILE/system.254.939393617’ repair wait; Diskgroup altered.

SQL> alter diskgroup DG1 scrub disk DATA_DISK1 repair power max force; Diskgroup altered […]

12c Database : ASM Enhancements : New Replace Disk command

If an ASM disk becomes offline and cannot be repaired, administrators require the ability to replace the disk.

In prior versions of ASM, there was no replace command. Rather, administrators had to drop the faulty disk and then add a new one back into the disk group.

So,ASM level rebalance will takes place […]

12c Database : ASM Enhancements : Estimate the work for adding/deleting disks

Before 12C,we can only come know about estimate time of disk add/drop like expensive operation at diskgroup level. So,We could not predict how much time this will take in before hand .

In 12c ASM, a more detailed and more accurate work plan is created at the beginning of each rebalance operation.

In […]

12c Database : ASM Enhancements : FlexASM – Overview

Flex ASM is a new architecture in Oracle Cluster/Grid Infrastructure where you can reduce the foot print of ASM instances in the cluster. I.e you really do not need 4 ASM instances for 4 Nodes.

In addition to above, Flex ASM also alleviate the problem of RDBMS instance dependency on ASM instance. For instance, if […]