On Fri, Mar 20, 2009 at 1:53 PM, fooler mail <[email protected]> wrote: .. > the problem with rac is that it shared its backend storage... thus the > bottleneck and scalability problem comes when more nodes added to a > RAC especially when the nodes are doing a write operations... > furthermore.. oracle 11g can support now upto 100 nodes... in real > implementations.. it shows negative scalability because of the nodes > coordinating with each other to communicate who owns this resource > (eg. lock ownership). .. > i have experienced with oracle rac (10gR2) and experienced how it was > bog down the whole RAC system too.. tsk tsk tsk
Oracle is not exactly shared-everything. While the storage is indeed a single point of bottleneck, the existence of Cache Fusion means that you will not bottleneck the disk right away. As for lock contention... that's why in a correctly-configured RAC environment you MUST use the Partitioning option as well (that's an additional $10K+ / CPU, ka-ching!) and partition your tables properly so that you won't have lock contention. To simply say "in real implementatons RAC shows negative scalability" is a very common misconception and indeed, people see this in practice but it's because they don't know how to tune RAC. Shared-nothing is very challenging simply because you don't have a single system view. Most people don't have to have to aggregate their data from all over the place just to do a single query. In any case, in Oracle 11g the new Exadata storage cell concept allows linear scalability to very many nodes and removes the shared-storage requirement that RAC has (traditionally) had. -- Orlando Andico +63.2.976.8659 | +63.920.903.0335 _________________________________________________ Philippine Linux Users' Group (PLUG) Mailing List http://lists.linux.org.ph/mailman/listinfo/plug Searchable Archives: http://archives.free.net.ph
