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Are you running BTRFS with its built in RAID? That's been the biggest blocker for me. There have been numerous RAID bugs that have caused data-loss and I believ

by _ecqc 10y ago

Are you running BTRFS with its built in RAID? That's been the biggest blocker for me. There have been numerous RAID bugs that have caused data-loss and I believe at least one of them is still unpatched.

kzrdude 10y ago
I think Chris Mason is open with that raid support is not really stable yet, right? Status page says so: https://btrfs.wiki.kernel.org/index.php/Status https://btrfs.wiki.kernel.org/index.php/Status
- aarmenaa 10y ago
  As far as I know they consider RAID0, 1, and 10 to be stable. Last time I used it rebuilds were substantially slower than ZFS or mdraid. Rebuild performance seems to one of a few issues that BTRFS has had trouble solving. RAID 5 and 6 were declared stable last year, only to have that retracted when some fatal flaw was discovered that would apparently cause data loss if you needed to rebuild.
  - mshook 10y ago
    It's mostly true but the issues as far as I know are: - RAID 1 with more than 2 disks is not what you think it is: the data will be mirrored but only once, no matter how many disks you have (meaning if you have a mirror with 3 disks, you only have 2 copies of your data). Because in BTRFS lingo, RAID 1 means '2 copies of the data' https://btrfs.wiki.kernel.org/index.php/FAQ#What_are_the_differences_among_MD-RAID_.2F_device_mapper_.2F_btrfs_raid.3F https://btrfs.wiki.kernel.org/index.php/FAQ#What_are_the_dif... which is not what people expect from RAID 1 with more than 2 disks - RAID 1 always needs 2 disks to be working, if not you can't mount the thing... Well you can, but only once... https://btrfs.wiki.kernel.org/index.php/Gotchas#raid1_volumes_only_mountable_once_RW_if_degraded https://btrfs.wiki.kernel.org/index.php/Gotchas#raid1_volume... - RAID 10 inherits these special RAID 1 cases as a result Most of that stuff is described here: https://btrfs.wiki.kernel.org/index.php/Status https://btrfs.wiki.kernel.org/index.php/Status So as they say on the status page: "mostly ok"
lomnakkus 10y ago
My main issue isn't actually a single thing that's wrong -- it's the completely and utterly haphazard way many of the features in btrfs have been "designed"[1]. Some of these problem they've had seem, to me at least, to be a fundamental lack of a coherent design. That does not bode well for stability, even 10(?) years after its first version. bcachefs seems to have a much more coherent design. [1] "Oh, yeah, I don't know how to handle this code path yet, let's stick a BUG_ON in there! I'm sure we'll figure something out later."

by _ecqc 10y ago

kzrdude 10y ago

I think Chris Mason is open with that raid support is not really stable yet, right? Status page says so: https://btrfs.wiki.kernel.org/index.php/Status https://btrfs.wiki.kernel.org/index.php/Status

aarmenaa 10y ago
As far as I know they consider RAID0, 1, and 10 to be stable. Last time I used it rebuilds were substantially slower than ZFS or mdraid. Rebuild performance seems to one of a few issues that BTRFS has had trouble solving. RAID 5 and 6 were declared stable last year, only to have that retracted when some fatal flaw was discovered that would apparently cause data loss if you needed to rebuild.
- mshook 10y ago
  It's mostly true but the issues as far as I know are: - RAID 1 with more than 2 disks is not what you think it is: the data will be mirrored but only once, no matter how many disks you have (meaning if you have a mirror with 3 disks, you only have 2 copies of your data). Because in BTRFS lingo, RAID 1 means '2 copies of the data' https://btrfs.wiki.kernel.org/index.php/FAQ#What_are_the_differences_among_MD-RAID_.2F_device_mapper_.2F_btrfs_raid.3F https://btrfs.wiki.kernel.org/index.php/FAQ#What_are_the_dif... which is not what people expect from RAID 1 with more than 2 disks - RAID 1 always needs 2 disks to be working, if not you can't mount the thing... Well you can, but only once... https://btrfs.wiki.kernel.org/index.php/Gotchas#raid1_volumes_only_mountable_once_RW_if_degraded https://btrfs.wiki.kernel.org/index.php/Gotchas#raid1_volume... - RAID 10 inherits these special RAID 1 cases as a result Most of that stuff is described here: https://btrfs.wiki.kernel.org/index.php/Status https://btrfs.wiki.kernel.org/index.php/Status So as they say on the status page: "mostly ok"

lomnakkus 10y ago

My main issue isn't actually a single thing that's wrong -- it's the completely and utterly haphazard way many of the features in btrfs have been "designed"[1]. Some of these problem they've had seem, to me at least, to be a fundamental lack of a coherent design. That does not bode well for stability, even 10(?) years after its first version. bcachefs seems to have a much more coherent design. [1] "Oh, yeah, I don't know how to handle this code path yet, let's stick a BUG_ON in there! I'm sure we'll figure something out later."