On X2, X3, and X4 systems, high performance disks can execute about 300 small I/Os per second (IOPS) without a
large increase in response time (peak performance is actually above 400 IOPS), or 50,000 IOPS on a full rack. A
large I/O is roughly 3 times as expensive as a small IO. You can determine approximate disk utilization by counting
the total small I/Os and adding the total large I/Os multiplied by 3. Then compare this count to the 300 IOPS
threshold to determine utilization. For 4TB high capacity disks, the IOPS are around 120 and the multiplier for large
I/Os is about 2.
4TB high capacity disks have IOPS around 190 or 32,000 IOPS for a full rack and should also use a 2x multiplier for
large I/Os. For additional Exadata capacity details please reference the Oracle Exadata Database Machine Data
Sheets.
High disk latencies are not necessarily a problem – it depends on how the application is impacted. For a Data
Warehouse it may be perfectly fine for the disks to be running at maximum throughput and latency when processing
queries.
The xCapture and xtop eBPF tools are now in beta, with a demo dataset
-
The title says it all, I think it’s time to call the xcapture and xtop
toolset a beta version now. There are plenty of bugs, issues and
shortcomings to fix...
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