Error when building RAID-5 on FEMU drives

[NeverMore2744]

I tried to build a RAID-5 system on 7 emulated black-box SSDs with mdadm. After the parity creation finished (RAID-5 starts writing parities upon the RAID creation), the FEMU crashes with the error:

fvm login: [FEMU] FTL-Err: No free lines left in [vSSD6].

Is it related to the overprovisioning of SSDs?
Is it possible to use mdadm to build a RAID system with FEMU emulated drives without errors?

[huaicheng]

Is it related to the overprovisioning of SSDs?

Yes, any misconfigrations in your setup? Make sure the nvme device capacity exposed to the host is less than the raw nand flash capacity.

Is it possible to use mdadm to build a RAID system with FEMU emulated drives without errors?

Yes, by default it should work fine.

[NeverMore2744]

Thanks for your reply. I create the black-box SSD like this:

-device femu,devsz_mb=16384,femu_mode=1

It seems that both the capacity exposed to the host and the raw nand flash capacity are 16GiB. If all the capacity is written, it causes the error.
Now I found that I can specify the --size parameter in mdadm so that it does not use all 16GiB for RAID, and mdadm can run normally.