Comment by imiric

I'm currently troubleshooting an issue on my Proxmox server with very slow read speeds from a ZFS volume on an NVMe disk. The disk shows ~7GBps reads outside of ZFS, but ~10MBps in a VM using the ZFS volume.

I've read other reports of this issue. It might be due to fragmentation, or misconfiguration, or who knows, really... The general consensus seems to be that performance degrades after ~80% utilization, and there are no sane defragmentation tools(!).

On my NAS, I've been using ext4 with SnapRAID and mergerfs for years without issues. Being able to use disparate drives and easily expand the array is flexible and cost effective, whereas ZFS makes this very difficult and expensive.

So, thanks, but no thanks. For personal use I'll keep using systems that are not black boxes, are reliable, and performant for anything I'd ever need. What ZFS offers is powerful, but it also has significant downsides that are not worth it to me.