Today I will talk about some new features for ASM on 12c version.
Oracle Flex ASM
Oracle Flex ASM is a set of new features that provide critical capabilities required for cloud computing. Oracle Flex ASM redefines the traditional ASM cluster architecture of having one ASM instance on every node in the cluster; this means you can have less ASM instances than nodes in your cluster. In this configuration the number of ASM instances running is called ASM cardinality, by default the ASM cardinality is 3 and can be changed with a Clusterware command.
What are the benefits?
On the traditional architecture when an ASM instance fails; all DB instances connected to that instance in the node will also fail. With Oracle Flex ASM if the ASM instance fail the Clusterware will relocate that ASM instance to a different node and the DB instances will remotely (through private network) connect to the relocated ASM instance, all without disruption to the DB client.
Dedicated ASM Network
This new 12c feature provides the option to dedicate a private network for ASM network traffic only. There’s also the option to use the Oracle Clusterware interconnect private network.
As per the new Oracle Flex ASM feature, the DB instance can remotely connect to ASM instance hence the need of a password file in order to authenticate remote DB instances to ASM. Oracle Flex ASM has the ability of storing password files in a Disk Group and is extended to DB clients; this is really useful to avoid synchronizing multiple password files within the cluster.
Oracle Flex ASM is one of the most important enhancements to ASM in 12c version, however in the below whitepaper describes the rest of new features present.
Bertrand Drouvot has already tested this Oracle Flex ASM feature and uploaded the contents into his own blog (http://bdrouvot.wordpress.com/2013/06/29/build-your-own-flex-asm-12c-lab-using-virtual-box/).
Another interesting feature is the Extent Reading Selection Enhancement which evenly distributes the selection of which copy of a block is read in ASM Disk Groups with normal or high redundancy. This feature is enabled by default in 12c and states that users on I/O bound systems should notice a performance improvement while reading blocks from disks.