Can't use fio to check performace of mergerfs

[khaidox]

I can't use fio to check perfomace of mergerfs:

1. Setup via Command Line

mergerfs -o cache.files=libfuse /disk1:/disk2 /media

2. Run fio

• Use bs=1M
  fio --name=test --filename=/media --rw=read --bs=1M --numjobs=32 --runtime=20 --iodepth=8 --direct=1 --ioengine=libaio

fio: blocksize is larger than data set range
fio: blocksize is larger than data set range
fio: blocksize is larger than data set range
fio: blocksize is larger than data set range

I get this message

• Use bs=100
  fio --name=test --filename=/media --rw=read --bs=100 ....

fio: looks like your file system does not support direct=1/buffered=0
fio: destination does not support O_DIRECT
fio: pid=1705728, err=22/file:filesetup.c:805, func=open(/media), error=Invalid argument
fio: pid=1705726, err=22/file:filesetup.c:805, func=open(/media), error=Invalid argument
fio: pid=1705727, err=22/file:filesetup.c:805, func=open(/media), error=Invalid argument
fio: looks like your file system does not support direct=1/buffered=0
fio: destination does not support O_DIRECT

I wonder if can I use fio to check performace of mergerfs?
Note: If I use RAID0, I can use fio to check performace

[trapexit]

1. Please include information in tickets as request. I really can't comment on things intelligently without those details.
2. O_DIRECT is only partially supported due to the limitations of FUSE. Newest versions of mergerfs now somewhat support O_DIRECT but not fully.