Oracle Database Appliance includes solid-state drives (SSDs) to enhance storage performance.
Oracle Database Appliance includes solid-state drives (SSDs) to enhance the performance of certain operations. SSDs increase the speed of storage operations by accelerating redo log writes, caching database data more efficiently than standard disk drives, and improving read/write (I/O) performance for database files.
Accelerating Redo Log Writes
Accelerating Redo Log Writes
Oracle Database Appliance contains four dedicated SSDs in slots 20 through 23 specifically for database redo logs. An Oracle ASM disk group named +REDO with High Redundancy is provisioned during the deployment process to accelerate database redo log write operations and improve latency. Databases automatically utilize these SSDs, and no other files can be hosted on them.
Caching Database Data
Oracle Database Appliance X5-2 introduces four additional 400 GB SSDs in slots 16 through 19 that can be used to host database files, or as a database flash cache in addition to the buffer cache.
An Oracle ASM disk group named +FLASH with Normal Redundancy is provisioned on these SSDs. All of the storage in the +FLASH disk group is allocated to an Oracle ASM Dynamic Volume (flashdata), and formatted as an Oracle ACFS file system. Storage in this flashdata file system is then made available as an Oracle ACFS file system and is used to create database flash cache files that accelerate read operations. The file that contains the flash cache is automatically created for each database and is specified using the database init.ora parameter db_flash_cache_file. By default, db_flash_cache_size is set to 3 times the size of SGA, up to 196 GB, unless there is not enough space, in which case the size parameter is set to 0. After you change the db_flash_cache_size parameter, you must restart the database to use the newly sized flash cache.
Improving I/O Performance for Database Files
Oracle Database Appliance Manager Configurator and Oracle Appliance Manager (OAKCLI) both give you the option to configure your appliance to store entire databases in flash memory using the flash data Oracle ACFS file system on 400 GB SSDs. These SSDs are also used for the database flash cache.
The OAKCLI command oakcli create database gives you the option to create the database using the SSD drives for data file storage. If there is not enough space available in the +FLASH disk group, then the oakcli create database command does not prompt you with the option to store the database data files on the SSD drives. Database files instead are created automatically in the +DATA disk group. You can also store database data files on both flash and hard disk drives. However, you must manage this storage allocation manually. Oracle recommends that you attempt to manage your files on both flash and hard disk files only if you have an advanced storage administrator understanding of database usage patterns
Your Oracle Database must meet the following requirements to use SSDs for data file storage:
Oracle Databases must be release 11.2.0.4 or later
The database types must be OLTP
Oracle Databases stored completely in the +FLASH storage space must be non-container databases (non-CDBs).
There must be 160 GB of available space in the +FLASH disk group.
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