Write Cache Setting
638051Dec 16 2009 — edited Dec 13 2012We are using Oracle RAC 10.2g in Window 2003. The installation guide of RAC said that we have to disable "Write Cache" in Device Manager->Disk->Policy->Uncheck "Enable Write Cache on disk". However, we found that the performance is very poor after disable the write cache and we tried the database import using one node andd the other node disabled. The performance for enable and disable is about 10 time slower.
Referring to the metalin "RAC: Frequently Asked Questions [ID 220970.1]"
....My customer wants to understand what type of disk caching they can use with their Windows RAC Cluster, the install guide tells them to disable disk caching?
If the write cache identified is local to the node then that is bad for RAC. If the cache is visible to all nodes as a 'single cache', typically in the storage array, and is also 'battery backed' then that is OK....
Since we are using DS4000 series SAN, this appliance could enable write cache at LUN level. However, after the setup, no performance gain can be observed. Will the setup in device manager (Uncheck "Enable Write Cache on Disk") affect the write cache in SAN storage ? Thanks !