What is ExaFusion Direct to Wire OLTP Protocol?
Martin Linxfeld (aka Luke Martin Feldman)
OCI Cloud Evangelist | DevOps & Terraform Advocate | Multicloud Expert | Followed by 30,000+ Professionals Worldwide
Have you ever experienced Oracle performance problem caused by RAC interconnect? Maybe you have noticed lots of gc cr request wait events? Yes, that is very common in RAC environment, when RAC traffic is using slow connection. However in Exadata we have InfiniBand which means 40 Gbps in each direction. Yes, InfiniBand has great throughput! But let's be honest - OS network stack per message overhead limits small message rate. For that reason in Patch Bundle 12.1.0.2 something new has arrived and it is called ExaFusion Direct to Wire OLTP Protocol. This new feature reimplements the RAC Cache Fusion with the bypass of the networking software stack, interrupts and scheduling. As you can see below on the picture, the speedup is significant even you compare it with simple InfiniBand. On the other hand you need to know that Exafusion is not supported on first two generations of Exadata (V1 & V2).
That is all for tonight. See you soon :-)
Picture 1. InfiniBand Exafusion Speedup
