Hi. Which filesystems are considered stable and recommended for a reliable bcache setup in 2024? There’s a lot of misinformation on the internet dating back to several years and I wanted to feel confident in using bcache for my home NAS server. I have done some of my own experiments and “speed benchmarks”, noting that XFS and EXT4 filesystems seem to be the “fastest” when compared to say btrfs and zfs. My use case is NAS media server where I want to be very greedy with catching everything on first write or first read, so my HDDs can go back to sleep/idle/low-power state. My bcache configuration used on my experiments and “cheatsheet” is here: https://github.com/TheLinuxGuy/ugreen-nas/blob/main/bcache-cheatsheet.md High-level insights on hardware and my goals: * 4 to 6 large capacity hard disks of mixed sizes (18TB, 14TB, 10TB, 20TB) * 2x 1TB NVME PCIE 3.0 x4 Samsung and WD, configured on RAID1 mdadm, /dev/md0p1 which is 85% of total available space. The remaining 15% of the nvmes are left empty on /dev/md0p2 following recommendations in this mailing list about “blkdiscard” (because Arch Linux bcache article scares you of using “discard” option natively in bcache) * Would like my 4-6 backing disks to be RAID5, so 1 disk failure can occur. Some experiments and benchmarks I have done on my own and its results: - mdadm + bcache + btrfs (no lvm): https://github.com/TheLinuxGuy/ugreen-nas/blob/main/experiments-bench/mdadm-bcache-btrfs.md - same but LVM2 on top: https://github.com/TheLinuxGuy/ugreen-nas/blob/main/experiments-bench/mdadm-lvm2-bcache-btrfs.md - ZFS monster with custom settings and bcache: https://github.com/TheLinuxGuy/ugreen-nas/blob/main/experiments-bench/mdadm-lvm2-bcache-zfs.md OK sorry for the wall of text. Please help me understand and recommend: 1) Can I trust bcache “discard” on my nvme /dev/md0 RAID1, or should I stick with blkdiscard on blank partition2? 2) Can I fully rely on btrfs as a filesystem on top of bcache? Setup like mdadm + lvm2 vol (bcache backing) 3) Any other warnings, recommendations, suggestions or things to consider? The reason for btrfs over all others is: snapshots, ability to shrink filesystem and expand it at will. LVM2 is used for stitching up disks of different sizes with the least amount of wasted disk space. Thanks Giovanni
