Cache Fusion Making Shared Storage Perform for Vanilla Systems RAC Architecture

Shared Nothing Shared Storage  Hard data partitions  Reroute query fragments  2pc  Different QP than SMP  Move query to data  No required partitions  Query processed one site  DLM  Disk ‘ping’  Move data to query A marketing slide follows

Change nodes online Oracle9i Real Application Clusters -- Scalability and High Availability Shared Cache Architecture using Cache Fusion Scales all applications out of the box Change disks w/o re-partitioning Shared Cache Cache Fusion Shared storage without the disk ping cost Standard h/w – SAN and fast IPC ipc san

What is Cache Fusion?  Coherency strategy for cluster database cache  Current block sent across interconnect  Integrates DLM & cache  “GCM”  Less I/O (compared to disk ping)  Less latency to get block

99 Fusion on contended block – initial state 10 0 Req X Node 1 Node 2 2: x-? D: ? x-? Cache hole GCM shadow Dirty Log record 10 0 Dirty current GCM master

Fusion on contended block - request 10 0 Req X x-? : x-? D: ? Function call

Fusion on contended block - ping 10 0 Req X x-? : x-? D: ? Ping (“bast”) message

Fusion on contended block – log wait 10 0 Req X x-? : x-? D: ? Group committed log write, usually already done before ping

Fusion on contended block – ship block 10 0 X-100 pi “Past Image” 2: x-? “consign” message in the block shipped by remote DMA

Fusion on contended block – adoption 10 0 X-100 2: pi-100 1: x-100 D: ? pi “adopt” terminates request, sets master state. Modification to version 101 while adopt is in flight.

Conveniently, there is no time to discuss  How we write blocks and get rid of the PIs  All the failure scenarios

Single Node Two Nodes Four Nodes # of users Does it work?