I am testing Mergerfs to bundle two SSD drives, in order to handle a large database that was surpassing the single drive capacity. This database is run by a process that uses extensively large memory mapped files, on a high RAM (64 GB) Ubuntu server.
Still, the process starts fine from the Mergerfs mount point, with very reasonable resource usage, but after a few hours Mergerfs is staying over ~100% CPU usage, and the whole system lags noticeably.
Trapexit, developer for Mergerfs, suggested to bring it here since it could be essentially a FUSE issue, perhaps to do with caching. I will probably switch to another device management scheme like LVM, but if there's any details I can provide about my issue, please let me know.