Oracle RAC Global Cache Load Profile from an AWR report provides a snapshot of inter-node communication efficiency.
Below is an example:
| Per Second | Per Transaction | |
|---|---|---|
| Global Cache blocks received: | 227.44 | 1.56 |
| Global Cache blocks served: | 56.49 | 0.39 |
| GCS/GES messages received: | 332.53 | 2.28 |
| GCS/GES messages sent: | 535.63 | 3.67 |
| DBWR Fusion writes: | 4.56 | 0.03 |
| Estd Interconnect traffic (KB) | 2,441.02 |
The “received” and “served” block counts align with those in the Load Profile section.
Interconnect traffic reflects the volume of data your RAC nodes exchange over the private network.
- Too low indicates underutilization — wasted scalability potential.
- Too high suggests inefficiency — possibly hot blocks thrashing across nodes.
We can estimate the interconnect traffic by assuming an 8KB block size (typical for Oracle) and roughly 200 bytes per GCS/GES message:
(227.44 + 56.49) * 8 + (332.53 + 535.63) * 200 / 1024 = 2441.00 KB
This calculation nearly matches the reported 2,441.02 KB/sec.
A throughput of around 2.4 MB/sec is fair quiet for a mid-sized RAC system — well below the 1–10 GB/sec range that might indicate network contention.
Yuan Yao, An Oracle ACE's Blog 
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