Re: How to debug intermittent increasing md/inflight but no disk activity?

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On 13/07/2024 01:45, Dave Chinner wrote:

That's irrelevant to the problem being discussed. The OP is
reporting stalls due to the bursty incoming workload vastly
outpacing the rate of draining of storage device. the above comment
is not about how close to "raw performace" the MD device gets on
NVMe SSDs - it's about how much faster it is for the given workload
than HDDs.


NVMe raid is faster than HDD raid, that is true. Relative performance
degradation is a different matter. When used with the default bitmap
settings MD raid sends a ton of disk flushes, even with full stripe writes,
and that kills the already atrocious performance.

OP should modify his array and remove or move the bitmap to an external
drive and see how much that will help.





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