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.
