4 ms·

BtrFS is unsafe for production use unless it's coupled with really good backups. On the other hand, NTFS on Windows, Ext* on Linux, or ZFS on any supported OS,

BtrFS is unsafe for production use unless it's coupled with really good backups. On the other hand, NTFS on Windows, Ext* on Linux, or ZFS on any supported OS, has not been known to eat data as frequently.

winter_blue 4y ago
Is BtrFS without RAID safe? According to them (https://btrfs.wiki.kernel.org/index.php/Status https://btrfs.wiki.kernel.org/index.php/Status) only RAID56 is unstable.
- rleigh 4y ago
  There are still major bugs in the rest of it. You can trivially corrupt a mirror. There are examples for how to reproduce it exactly in qemu with virtual drives. I caused me total dataloss on my first Btrfs filesystem at least 8 years back. That bug is apparently still there. The unbalancing issues are still there. I have zero trust of Btrfs in any form.
  - leetnewb 4y ago
    Can you link to that? I have been using btrfs in raid1 and single for ~3-4 years now without any data loss.
    - rleigh 4y ago
      You (and many others) might well be using RAID1 mirrors without problems. I did as well. But the problems here are not encountered during day-to-day usage. They are bugs in the recovery codepaths following hardware failures. I suffered this due to a transient SATA cable glitch, but the instructions let you exactly reproduce this with qemu with a recent kernel. I've not tried the qemu approach myself; I moved over to ZFS a good while back now. I've had a hunt for the specific instructions but I'm afraid I can't find it again with a search. The gist of it was to: - create Btrfs mirror using two qemu virtual disks - pull the (virtual) plug on one of the pair to disconnect it, then later reconnect it - Btrfs ends up hosing both the outdated and current copies of the mirror, leading to complete dataloss of the entire mirror
Tijdreiziger 4y ago
Synology uses Btrfs + mdadm RAID for their NAS boxes, which are regarded as rock-solid. https://www.synology.com/en-global/dsm/Btrfs https://www.synology.com/en-global/dsm/Btrfs
- selfhoster11 4y ago
  Whatever voodoo they are pulling out of thin air, is clearly not present on commodity, non-tuned Btrfs filesystems. That, and most people have backups set up on their NAS.
  - Tijdreiziger 4y ago
    Well, if you want, you can just pull the drives out of your Synology box and hook them up to any Linux system [1]. So whichever way they're tuning it, it can't be that voodoo-esque. [1] https://kb.synology.com/en-global/DSM/tutorial/How_can_I_recover_data_from_my_DiskStation_using_a_PC https://kb.synology.com/en-global/DSM/tutorial/How_can_I_rec...
chasil 4y ago
With all due respect, this is now far from true. "So, we'll repeat this once more: as a single-disk filesystem, btrfs has been stable and for the most part performant for years." https://arstechnica.com/gadgets/2021/09/examining-btrfs-linuxs-perpetually-half-finished-filesystem/ https://arstechnica.com/gadgets/2021/09/examining-btrfs-linu...

winter_blue 4y ago

Is BtrFS without RAID safe? According to them (https://btrfs.wiki.kernel.org/index.php/Status https://btrfs.wiki.kernel.org/index.php/Status) only RAID56 is unstable.

rleigh 4y ago
There are still major bugs in the rest of it. You can trivially corrupt a mirror. There are examples for how to reproduce it exactly in qemu with virtual drives. I caused me total dataloss on my first Btrfs filesystem at least 8 years back. That bug is apparently still there. The unbalancing issues are still there. I have zero trust of Btrfs in any form.
- leetnewb 4y ago
  Can you link to that? I have been using btrfs in raid1 and single for ~3-4 years now without any data loss.
  - rleigh 4y ago
    You (and many others) might well be using RAID1 mirrors without problems. I did as well. But the problems here are not encountered during day-to-day usage. They are bugs in the recovery codepaths following hardware failures. I suffered this due to a transient SATA cable glitch, but the instructions let you exactly reproduce this with qemu with a recent kernel. I've not tried the qemu approach myself; I moved over to ZFS a good while back now. I've had a hunt for the specific instructions but I'm afraid I can't find it again with a search. The gist of it was to: - create Btrfs mirror using two qemu virtual disks - pull the (virtual) plug on one of the pair to disconnect it, then later reconnect it - Btrfs ends up hosing both the outdated and current copies of the mirror, leading to complete dataloss of the entire mirror

Tijdreiziger 4y ago

Synology uses Btrfs + mdadm RAID for their NAS boxes, which are regarded as rock-solid. https://www.synology.com/en-global/dsm/Btrfs https://www.synology.com/en-global/dsm/Btrfs

selfhoster11 4y ago
Whatever voodoo they are pulling out of thin air, is clearly not present on commodity, non-tuned Btrfs filesystems. That, and most people have backups set up on their NAS.
- Tijdreiziger 4y ago
  Well, if you want, you can just pull the drives out of your Synology box and hook them up to any Linux system [1]. So whichever way they're tuning it, it can't be that voodoo-esque. [1] https://kb.synology.com/en-global/DSM/tutorial/How_can_I_recover_data_from_my_DiskStation_using_a_PC https://kb.synology.com/en-global/DSM/tutorial/How_can_I_rec...

chasil 4y ago

With all due respect, this is now far from true. "So, we'll repeat this once more: as a single-disk filesystem, btrfs has been stable and for the most part performant for years." https://arstechnica.com/gadgets/2021/09/examining-btrfs-linuxs-perpetually-half-finished-filesystem/ https://arstechnica.com/gadgets/2021/09/examining-btrfs-linu...