Oracle Database 12c and 18c Enterprise Edition provide efficient, reliable, and secure data management for mission-critical transactional applications, query-intensive data warehouses, and mixed workloads. Oracle Real Application Clusters (RAC) provides the processing power of multiple, interconnected servers on a cluster; enables access to a single database from multiple servers within the cluster. This design insulates both applications and database users from server failures, while providing performance that scales out on-demand at low cost; and is a vital component of grid computing that enables multiple servers to share a database. Oracle Database 12c and 18c include Automated Storage Management (ASM) and Oracle Clusterware. Combining the use of ASM and Oracle Clusterware virtualizes storage, database servers, application servers, holistic management, and all the other aspects related to deploying and managing a virtualized IT environment.
Oracle ASM is Oracle's recommended storage management solution that provides an alternative to conventional volume managers, file systems, and raw devices. Oracle ASM is a volume manager and a file system for Oracle Database files that supports single-instance Oracle Database and Oracle Real Application Clusters (Oracle RAC) configurations.
ASMLIB, UDEV, and the ASM filter drivers are all supported, although, Dell EMC recommends only using the ASM Filter Driver with 12c or greater. Use the solution that best meets your business and technical needs. ASMLIB is generally aligned with Oracle Linux and/or the Unbreakable Kernel, while Udev is customarily used with other UNIX distributions. The new filter driver seeks to prevent unintentional out-of-band writes to devices allocated to your database. It also supports TRIM and provides integration with other storage APIs as they develop.
Oracle ASM uses disk groups to store datafile; an Oracle ASM disk group is a collection of disks that Oracle ASM manages as a unit. Within a disk group, Oracle ASM exposes a file system interface for Oracle Database files. The content of files that are stored in a disk group is evenly distributed to eliminate hot spots and to provide uniform performance across the disks. The performance is comparable to the performance of raw devices.