I went back and forth with Hetzner a couple times, I think we just got a bad machine :)

I've been saying it for months, but eventually I'm going to move the automated builds off the 48 core monster and we'll be able to use that for automated perf testing too. The machine we just got has spindles for EC perf testing, but the Hetzner monster has very high end enterprise ssdd.

Also, just got done with the Rust for Linux conference, still not home but here's slides that still need reformatting: https://evilpiepirate.org/~kent/Kangrejos-2026-bcachefs.pdf

Love to hear that there will be more real hw tests. At the moment I am building NAS and used your benchmark for evaluating the filesystems. I am glad to see that your data roughly matches mine (apart from scrub which on 4x 6tb HDDs took 15 hours for md-raid10 while CoW systems took seconds). Personally I found that array of HDDs behaves very differently than GH runner (my feeling is that since it runs on same disk you are testing theoretical throughput rather than ability to utilize disks). My tests gave an idea for following topologies:

  * 4 HDDs (for example dm-raid has read balancing optimized specifically for HDDs)
  * 5 HDDs (classical raid should see no improvement but btrfs and bcachefs should balance the load)
  * 4 SSDs
  * 3 HDDs + 1 SSD no tiering
  * 2 HDDs + 2 SSD no tiering
  * 1 drive 10x larger than others (since how bcachefs and btrfs allocators work)
  * nocow

Thanks for awesome work

I have three identical Lenovo SFF PCs with a U.2 SSD in each. I'm currently running them in a Ceph cluster but I'll be tearing that down soon. I could run some benchmarks with three in one box and report back? Would be a one-time thing rather than an on-going commitment though.

Disregard, I just saw you have some RAID10 tests in there so three SSDs won't be enough.

Should include:

1. Dual Ext4 + external 32GB journal X4 pcie SSD (the prior winner of benchmark surveys)

2. Bare F2FS after a trim and SSD vendor software cache flush operation (it should be slower, but knowing how much slower on identical hardware could be interesting.)

3. DRBD across a 48U 100Gbps host rack (single X4 pcie data drive per host, OS on primary)

4. CephFS across a 48U 100Gbps host rack (single X4 pcie data drive per host, OS on primary)

Best regards =3