On Thu, Jul 11, 09:12, Dave Chinner wrote > > Of course it’s not reproducible, but any insight how to debug this next time > > is much welcomed. > > Probably not a lot you can do short of reconfiguring your RAID6 > storage devices to handle small IOs better. However, in general, > RAID6 /always sucks/ for small IOs, and the only way to fix this > problem is to use high performance SSDs to give you a massive excess > of write bandwidth to burn on write amplification.... FWIW, our approach to mitigate the write amplification suckage of large HDD-backed raid6 arrays for small I/Os is to set up a bcache device by combining such arrays with two small SSDs (configured as raid1). Best Andre -- Max Planck Institute for Biology Tel: (+49) 7071 601 829 Max-Planck-Ring 5, 72076 Tübingen, Germany http://people.tuebingen.mpg.de/maan/
