I've posted this over on the HPE Community but one of their moderators moved it to the wrong forum where it's unlikely to get much attention.
We've recently turned on Adaptive Flash Cache for the first time. Now we're seeing two errors; the first is from Infosite: "High slab space usage detected." The second is in Events & Alerts: "Flash Cache I/O times are slow on node: 3"
I've looked at some performance reports in SSMC. Looking at "user time", node 3 has been busier than the others for days/weeks. However, when we enabled Flash Cache a few days ago the "system time" metric for node 3 spiked above the other nodes and addition to user time.
Looking at Physical Drive Performance, I see that the SSDs do have some IOPs spikes, with write latency spiking to 22ms during one stat sample. All 16 SSD drives chart identically.
The report "Adaptive Flash Cache Performance" shows all four nodes charting pretty much identically. Flash Cache used percentage peaked at 400% roughly 20 hours after enablement but it's now slowly wobbling up and down between 300 to 400%. I would expect the cache to remain full once filled.
There are no other workloads on these SSDs (no CPGs).
Any thoughts?