Oracle ASM 19c - Features

 These are the new features for Oracle Automatic Storage Management 19c.

• SRVCTL command enhancements
• Flushing the password file metadata
• Automatic block corruption recovery with the CONTENT.CHECK disk group attribute
• New and updated ASMCMD commands
  • The password option with the ASMCMD pwcreate command is now optional.
  • The new ASMCMD setsparseparent command sets the parent for a sparse child file.
  • The new ASMCMD mvfile command moves a file to the specified file group in the same disk group where the file is stored.
• Support for Parity Protected Files

These are the new features for Oracle Clusterware Administration in Oracle 19c.

• Zero-downtime Oracle Grid Infrastructure Patching
• Provide an Alternate Network for Oracle Clusterware
• SRVCTL Changes for Oracle Clusterware 19c
• Rapid Home Provisioning Name Change
• Fine-Grained Single-Instance PDB Patching
• Zero-Downtime Oracle Grid Infrastructure Patching Using Fleet Patching and Provisioning
• Automated Transaction Draining for Oracle Grid Infrastructure Upgrades
• Oracle Restart Patching and Upgrading
• Support the Specification of TLS Ciphers Using CRSCTL

What's new in 19c - Part II (Automatic Storage Management - ASM)

Not too many features to talk on 19c ASM. Below is my hand-pick features of 19c ASM for this blog post.


Automatic block corruption recovery 

With Oracle 19c, the CONTENT.CHECK disk group attribute on Exadata and cloud environment is set to true by default. During data copy operation, if Oracle ASM relocation process detects block corruption, it perform automatic block corruption recovery by replacing the corrupted blocks with an uncorrupted mirror copy, if one is avialble.


Parity Protected Files Support

The level of data mirroring is controlled through ASM disk group REDUNDANCY attribute. When a two or three way of ASM mirroring is configured to a disk group to store write-once files, like archived logs and backup sets, a great way of space is wasted. To reduce the storage overahead to such file types, ASM now introduced PARITY value with REDUNDANCY file type property. The PARITY value specifies single parity for redundancy. Set the REDUNDANCY settings to PARITY to enable this feature.

The redundancy of a file  can be modified after its creation. When the property is changed from HIGH, NORMAL or UNPROTECTED to PARITY, only the files created after this change will have impact, while the existing files doesn't have any impact.

A few enhancements are done in Oracle ACFS, Oracle ADVM and ACFS replication. Refer 19c ASM new features for more details.


** Leaf nodes are de-supported as part of Oracle Flex Cluster architecture from 19c.

 Multiple ASMB

Given that +ASM1 has DG1 mounted but not DG2, and +ASM2 has DG2 mounted but not DG1, the Multiple ASMB project allows for the Database to use both DG1 and DG2 by connecting to both ASM instances simultaneously. Instead of having just ASMB, we can now have ASMBn.

 

This feature increases the availability of the Real Application Clusters (RAC) stack by allowing DB to use multiple disk groups even if a given ASM instance happens not to have all of them mounted.

Parity Protected Files:

A great deal of space is consumed when two or three way Oracle ASM mirroring is used for files associated with database backup operations. Backup files are write-once files, and this feature allows parity protection for protection rather than conventional mirroring. Considerable space savings are the result.

 

If a file is created as HIGH, MIRROR, or UNPROTECTED redundancy, its redundancy can change to HIGH, MIRROR, or UNPROTECTED. If redundancy has been changed, then the REMIRROR column of V$ASM_FILE contains Y to indicate that the file needs new mirroring, initiating a rebalance to put the new redundancy into effect. After the rebalance completes, the value in the REMIRROR column contains N .

 

When a file is created with PARITY redundancy, that file can never change redundancy.

 

When the file group redundancy property is modified from a HIGH, MIRROR, or UNPROTECTED setting to a PARITY setting, the redundancy of the existing files in the file group does not change. This behaviour also applies to a change from PARITY to a HIGH, MIRROR, or UNPROTECTED setting. However, any files created in the future adopt the new redundancy setting.