Should I use btrfs or ZFS for my 4-disk HDD setup? Each HDD has 16TB of space and I will use Raid 5 (btrfs) or RaidZ1 (ZFS)

GPT-5.4

Vote: ZFS

ZFS is the safer choice here. For a 4×16TB HDD array, RAID5/RAIDZ1 already carries meaningful rebuild risk because large disks take a long time to resilver, so you want the more mature and predictable implementation. btrfs RAID5/6 has had a long-standing reputation for edge-case correctness and recovery concerns. While btrfs is excellent in many roles, its RAID5/6 mode is still commonly treated with extra caution for important data. ZFS RAIDZ1 is widely deployed, battle-tested, and has stronger tooling around scrubs, resilvering, monitoring, and recovery behavior. If you must choose between these two exact options, ZFS is the more trustworthy option. That said, with 16TB disks, the bigger recommendation is to avoid single-parity entirely if the data matters. Prefer RAIDZ2 or a mirrored layout, because one disk failure during rebuild can turn into a very bad day.

Sonar Pro

Vote: ZFS

For your specific 4-disk 16TB HDD setup, ZFS with RaidZ1 is the superior choice due to critical stability and data integrity differences. Btrfs RAID5/6 are explicitly marked as unsafe for production use[3]. Multiple sources highlight that Btrfs RAID5 and RAID6 configurations have documented stability issues, slower write speeds, and unresolved concerns about data safety[5]. In contrast, ZFS's RaidZ1 is architecturally mature and well-tested, providing reliable single-disk failure protection. Data integrity is another decisive factor. ZFS implements end-to-end checksumming with self-healing mechanisms and uses the Dirty Time Log (DTL) to track block updates during temporary device offline events[3]. Btrfs lacks equivalent mechanisms—if a disk temporarily goes offline and reappears, Btrfs immediately treats it as valid without reconciling missed writes, risking silent data corruption[3]. This vulnerability is particularly concerning with HDDs, which are more prone to temporary failures than SSDs. Performance-wise, ZFS RAID support and its 128-bit scalability offer better performance compared to Btrfs[1]. For your use case with large 16TB drives, ZFS's more efficient RAID implementation is preferable. Your 4-disk setup fits well within RaidZ1's recommended configuration (not wider than about five disks)[7], making it an ideal scenario for ZFS deployment. While ZFS has higher RAM requirements, this is a worthwhile trade-off for the substantially greater reliability and data safety it provides.

Grok 4.1 Fast

Vote: ZFS

BTRFS RAID5 is notoriously unstable and prone to data corruption, especially during resilvering on large 16TB HDDs. Multiple reports and BTRFS developers themselves advise against using it for production setups due to unresolved bugs that can lead to total pool loss. ZFS RAIDZ1, while also single-failure tolerant like RAID5, is far more mature, battle-tested in enterprise and NAS environments (e.g., TrueNAS), with robust checksums, self-healing, and scrub-based integrity checks that handle bit rot effectively on HDDs. ZFS offers superior features like inline compression, efficient snapshots, and deduplication, with lower risk for a 4-disk setup. On Linux, OpenZFS is stable and performant, making it the safer choice despite slightly higher RAM needs.

Gemini 3.1 Pro

Vote: ZFS

You should absolutely choose ZFS (RAIDZ1) over btrfs (RAID 5) for this setup, primarily due to the severe, well-documented instability of btrfs in RAID 5/6 configurations. Btrfs RAID 5/6 suffers from a fundamental flaw known as the "write hole." If a power failure or crash occurs during a write, it can silently corrupt your parity data, potentially leading to catastrophic data loss during a rebuild. The btrfs community itself strongly discourages using its RAID 5/6 profiles for any critical data. On the other hand, ZFS is highly mature, enterprise-tested, and its copy-on-write architecture completely avoids the write hole issue. RAIDZ1 is rock-solid and will reliably protect your data against a single drive failure. As a side note, because 16TB drives take a very long time to rebuild (resilver), the risk of a second drive failing during the rebuild process is non-trivial. While RAIDZ1 is much safer than btrfs RAID 5, you might also want to strongly consider RAIDZ2 (equivalent to RAID 6) for drives of this size to guarantee maximum peace of mind.

Claude Opus 4.6

Vote: ZFS

ZFS with RAIDZ1 is the clear choice here for several critical reasons: **BTRFS RAID 5 is fundamentally broken.** The btrfs wiki itself marks RAID 5/6 as unstable and warns against using it for production data. It suffers from a well-known "write hole" problem that can lead to data loss, especially during power failures or crashes. This issue has remained unresolved for years despite ongoing development. **ZFS RAIDZ1 is battle-tested and mature.** RAIDZ1 has been production-ready for nearly two decades. It was designed from the ground up to handle the exact use case you're describing — a multi-disk redundancy setup with data integrity guarantees. It has no write hole issue thanks to its copy-on-write transactional model. **Data integrity is superior with ZFS.** ZFS checksums every block of data and metadata, detecting and automatically repairing bit rot and silent data corruption during scrubs or reads. While btrfs also checksums data, the broken RAID 5 implementation means the repair mechanisms cannot be relied upon in a degraded or error state. **With 16TB drives, you need reliability.** Larger drives take longer to resilver/rebuild and have higher URE (Unrecoverable Read Error) risks during reconstruction. ZFS's proven resilver process and robust error handling make it far more trustworthy for large-capacity drives. You might even want to consider RAIDZ2 (equivalent to RAID 6) with drives this large, which ZFS handles excellently. **ZFS has a richer feature set for storage management.** Snapshots, send/receive for backups, native compression, deduplication (if needed), and dataset-level quotas are all mature and reliable in ZFS. The only real downsides of ZFS are higher RAM usage (easily mitigated with 16-32GB of RAM) and the licensing situation on Linux (DKMS module rather than in-tree). Neither of these comes close to outweighing the risk of data loss from btrfs RAID 5.

Kimi K2.5

Vote: ZFS

For a 4-disk parity setup with 16TB drives, ZFS is significantly safer. RAIDZ1 is mature and production-ready, while btrfs RAID5 has a troubled history with the 'write hole' problem and stability issues that persist despite recent improvements. With 16TB drives, rebuild times will stretch into days, putting enormous stress on the remaining drives. ZFS handles this resilver process more robustly with end-to-end checksums that detect silent corruption during rebuilds, while btrfs lacks this comprehensive data integrity framework. The risk of a second drive failure during a long rebuild is real with large HDDs. ZFS's copy-on-write architecture eliminates the RAID5 write hole entirely, ensuring your array remains consistent even if power is lost during a critical operation. For irreplaceable data at this scale, ZFS's maturity and safety mechanisms make it the clear choice.

Final Summary

The AI Roundtable reached a rare and absolute consensus, delivering a unanimous rejection of btrfs RAID 5 in favor of ZFS. Models like Claude Opus 4.6 and Gemini 3.1 Pro were particularly blunt, characterizing the btrfs implementation as 'fundamentally broken' due to its notorious 'write hole' flaw, while GPT-5.4 and Kimi K2.5 emphasized the terrifyingly long rebuild times of 16TB drives as a reason to stick with a battle-tested architecture.

No agreement after 1 rounds of discussion. Final vote: ZFS: 6

Strongest Arguments

• ZFS: The btrfs wiki itself marks RAID 5/6 as unstable and warns against its use for production data; ZFS’s copy-on-write architecture and transactional model inherently solve the 'write hole' problem that has plagued btrfs for years.