3.4.5.2 Enabling Write Back Flash Cache on a Rolling Basis for Software Versions Lower Than 11.2.3.3.1
You can enable Write Back Flash Cache on a rolling basis.
To modify the Flash Cache attribute from writethrough
to writeback
, the Flash Cache must be dropped first. For Oracle Exadata System Software releases prior to 11.2.3.3.1, you must stop cell services or inactivate grid disks when enabling Write Back Flash Cache.
There is a shell script to automate enabling and disabling Write Back Flash Cache. Refer to My Oracle Support note 1500257.1 for the script and additional information.
Note:
Any time the Flash Cache is dropped and re-created, there is a performance impact for database operations. While the Flash Cache is being repopulated, there are more cache misses, which impacts database performance.Oracle Grid Infrastructure homes and Oracle Database homes must at release 11.2.0.3 BP9 or higher to use write-back Flash Cache. Refer to My Oracle Support note 888828.1 for the minimum release requirements for Oracle Exadata System Software, Oracle Grid Infrastructure home, and Oracle Database home.