Cache: ARC Evicted Bytes

This statistic shows bytes that were evicted from the ZFS ARC, as part of its usual housekeeping. The breakdown allows L2ARC eligibility to be examined.

An understanding of ZFS ARC internals might be required to properly interpret this statistic.

When to Check ARC Evicted Bytes

This could be checked if you are considering to install cache devices (L2ARC) because this statistic can be broken down by L2ARC state. If L2ARC eligible data was frequently being evicted from the ARC, then the presence of cache devices could improve performance.

This might also be useful to check if you have issues with cache device warmup. The reason might be that your workload is not L2ARC eligible.

If there are caching issues on Oracle ZFS Storage Appliance, check the Cache: ARC Accesses statistic to see how well the ARC is performing, and the Protocol statistics to understand the requested workload. Then, check the Advanced Analytics Cache: ARC Size and Cache: ARC Evicted Bytes for further details on the ARC behavior.

ARC Evicted Bytes Breakdowns

Table 6-3 A Breakdown of ARC Evicted Bytes

Breakdown Description

L2ARC state

Shows L2ARC cached or uncached, and L2ARC eligible or ineligible.