Oracle 12c RAC New
Features
Oracle ASM Flex
This will help
reduce the overhead on the database server by running an ASM instance remotely.
Instances can use the remote ASM node for any planned or unplanned downtime as
well. All the metadata requests can be covered by non-local ASM instances. In
addition to that this feature removes the risk of single point of failure, of
having only one ASM instance for storage management. Now if a local ASM
instance fails, the database instance can now connect directly to any of the
other surviving remote ASM instances in the cluster.
ASM Disk Scrubbing
This monitors all
the disks in the ASM disk groups and will discover logical corruptions.
Normally these corruptions were discovered when an RMAN backup job ran. Disk
Scrubbing will try to automatically recover those logical corruptions without
the DBA even knowing!
Shared Password file in ASM
A single password
file can now be stored in the ASM diskgroup and can be shared by all nodes. No
need to have individual copies for each instance.
ASM Multiple
Diskgroup Rebalance and Disk Resync Enhancements
Resync
Power limit – Allows multiple diskgroups to be resynced concurrently.
Disk Resync Checkpoint – Faster recovery from instance
failures.
Grid Infrastructure Rolling Migration support for one-off’s
When applying a
one-off patch to the ASM instance, the databases that it is serving can be
pointed to use a different ASM instance.
Oracle Clusterware Flex Cluster
This feature may
appear similar to the ASM Flex feature but actually it is not. This is another
type of cluster that has been introduced in Oracle 12c. We need to understand
the two main components Hub Nodes and Leaf Nodes.
Hub Nodes are nodes that you currently see in the 11g
RAC architecture. Every node is a full-fledged node with the required
Clusterware software, share storage with a voting disk, interconnect network
etc. components. On the other hand the leaf nodes are lightweight
nodes with no shared storage and minimal Clusterware software. A leaf
node will be connected to a Hub Node.
Grid Home Server
This new feature
will allow you to have a single Golden Oracle Home on one of nodes and all
other nodes to be a client of that Golden Home. You will only have to patch the
single golden Oracle Home and rest will take it from there.
Application Continuity
This helps minimize
the application downtime caused by temporary failures in the infrastructure
and/or the database servers. This piece sits between the application and the
database working at the JDBC driver layer. If any failure
occurs and is recoverable, it will be recovered automatically
while being transparent to the application. The application will only observe a
minor latency delay in the transactions and the failure will automatically be
recovered transparently. Additionally Oracle guarantees the successful
completion of the in-flight transactions, eliminating the
chance of duplicate transactions. The purpose of leaf nodes is to include
application servers and other servers with additional software running on the
Oracle 12c Clusterware infrastructure. These leaf nodes will not have any
database instances running on them. If a leaf node goes down then there will be
no impact on Hub nodes either. This allows the flexibility to run leaf nodes on
Virtual Machines while Hub nodes can run on the actual physical machines.
IPv6 Support
IPv6 was supported
in Oracle database 11gr2 but was only available for a standalone database. In
12c Database, clients can also now connect to database in RAC
environments, using the IPv6 protocol. The
interconnect however still only supports IPv4. This feature helps the customers
meet the PCI, SOX and other Security Compliance standards.
Multiple SCAN’s Per Subnet
Now you can
configure multiple SCAN’s per subnet mask, per cluster. This obviously is made
available to provide redundancy.
GHCTL
The new ghctl
utility will improve patching process.
UI auto runs root.sh
Oracle UI will
execute the root.sh script on all nodes. You don’t have to do this on all nodes
manually.
Deprecated
Features
While it is good to
be familiar with the new features it equally if not more to be aware of what
features of RAC are being deprecated so plans can be made to move away from
those Deprecated feature and alternatives chosen.
Oracle Restart
Oracle Restart
feature which was provided as a part of the Oracle Grid Infrastructure has been
deprecated. It will be de-supported in future versions.
RAW/Block Storage Devices
Oracle Database 12c
and Oracle Clusterware 12c, no longer support raw storage devices. The files
must be moved to Oracle ASM before upgrading to Oracle Clusterware 12c.
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