Hacker News Reader

Comment by wyager | Hacker News Reader

ZFS RAID is the best RAID implementation in many respects. Hardware RAID is bad at actually fixing errors on disk (as opposed to just transparently correcting) and surfacing errors to the user.

BTRFS is frequently not considered stable enough for production usage.

ZFS has dozens of useful features besides RAID. Transparent compression, instant atomic snapshots, incremental snapshot sync, instant cloning of file systems, etc etc.

Yes, different ZFS implementations are mostly compatible in my experience, and they should become totally compatible as everyone moves to OpenZFS. FreeBSD 13 and Linux currently have ZFS feature parity I believe.

View on HN

>BTRFS is frequently not considered stable enough for production usage.

I'm not sure this is still true, especially after Facebook deployed it on millions of servers.

https://btrfs.wiki.kernel.org/index.php/Production_Users

So what you’re saying is, btrfs works if you can afford an ops/sre team on par with Facebook’s?

Do they really care if any one of those servers loses its data though? At that scale, you need higher level redundancy so it makes sense to prioritize filesystems for other features than how well they actually retain your data.

For example, detecting corruption would be more important than never having any, so that you can get IO errors and immediately kill the server before it serves bad data.

Specifically BTRFS's RAID5/RAID6 implementation is unstable and susceptible to data loss. Facebook doesn't use those RAID levels in production.

https://www.phoronix.com/scan.php?page=news_item&px=Btrfs-Wa...

https://btrfs.wiki.kernel.org/index.php/Gotchas#Parity_RAID

> BTRFS is frequently not considered stable enough for production usage.

synology NAS use btrfs by default. What is not stable?

Btrfs in single drive (and mirror/RAID1) modes are fine. The instability is in the RAID5/6 implementation[1]. Synology runs Btrfs (in single drive mode) on top of their own mdadm based RAID setup.

[1]: https://btrfs.wiki.kernel.org/index.php/RAID56

Reply on news.ycombinator.com