4 ms·

we're further along than btrfs in "will it keep my data"

by koverstreet 1y ago

tremon 1y ago
Fair enough, I have no practical experience with bcachefs myself.
- koverstreet 1y ago
  Fair :) I've been trying to keep this thing (relatively) quiet and low profile until it's completely done, but it's gotten hyped. Data integrity, core IO paths, all the failure modes, all the crazy repair corner cases - these are the hard parts if you really want to get a filesystem right. These are what we've been taking our time on. I can't claim 100% success rate w.r.t. data loss, but it's been phenomenally good, with some crazy stories of filesystems we've gotten back that you'd never expect - and then it just becomes the norm. I love the crazy bug reports that really push the boundaries of our capabilities. That's an attitude that reiserfs and btrfs never had, and when I am confident that it is 100% rock solid and bulletproof I'll be lifting the experimental label.
- sroussey 1y ago
  > I have no practical experience with bcachefs myself. Who does? When the MySQL and Postgres projects recommend it, I’ll have a look.
  - koverstreet 1y ago
    That's still a ways off, but it is worth noting that bcachefs handles database workloads in cow mode with no issue.
jcalvinowens 1y ago
> we're further along than btrfs in "will it keep my data" Honestly Kent, this continuing baseless fearmongering from you about btrfs is absolutely disgusting. It costs you. I was initially very interested in bcachefs, but I will never spend my time testing it or contributing to it as long as you continue behave this way. I'm certain there are many many others who would nominally be very interested, but feel the same way I do. Your filesystem charitably gets 0.001% the real world testing btrfs does. To claim it is more reliable than btrfs is ignorant and naive. Maybe it actually is more reliable in the real world (press X to doubt...), but you can't possibly know yet, and you won't know for a long time.
- rob_c 1y ago
  I'm happy to support that bcache may have a stable on disk format, but the lashing out at the alternatives is another example of behaviour I'd prefer to see dropped. If your product is so great its it's own advert. If it has problems spend the limited person power fixing it not attacking the opposition, this is what ciq have done, do better.
- koverstreet 1y ago
  We have documented, in this very thread, issues with multi device setups that btrfs has that bcachefs does not - and btrfs developers ignoring these issues. This isn't baseless fearmongering, this is "did you think through the failure modes when you were designing the basics". This stuff comes up over, and over, and over. Engineering things right matters, and part of that absolutely is comparing and documenting approaches and solutions to see what went right and what went wrong. This isn't a popularity contest, and this isn't high school where we form into cliques and start slinging insults. Come up with facts, documentation, analysis. That's what we do. I'm tired of these threads degenerating into flamewars.
  - kzrdude 1y ago
    (That's impressive, but the real world user pool is much smaller isn't. It still sounds like a proud brag more than it does proven by workload.) I am not a filesystems guy, but I was disappointed when I realized that btrfs did not have a good design for ENOSPC handling. So I'm curious, does bcachefs design for a benign failure mode when out of space?
    - koverstreet 1y ago
      We have enough user reports of multi device testing that they put both bcachefs and btrfs through, where bcachefs consistently survives where btrfs does not. We have much better repair and recovery, with real defense in depth. Now: I am not saying that bcachefs is yet trouble free enough for widespread deployment, we're still seeing cases where repair needs fairly minor work, but the filesystem may be offline while we get that fixed. OTOH we also recover, regularly, from absolutely crazy scenarios involving hardware failure: flaky controllers, lightning strikes, I've seen cases where it looked like a head crashed - took out a whole bunch of btree nodes in similar LBA ranges. IOW: the fundamentals are very solid, but keep checking back if you're wondering when it'll be ready for widespread deployment. Milestones to watch for: - 3 months with zero data loss or downtime events: I think we may get this soon, knock on wood - stable backports starting: 6.17, knock on wood (or maybe we'll be out of the kernel and coming up with our own plan, who knows) - weird application specific bugs squashed: these have been on the back burner, but there's some weird stuff to get to still (e.g. weird unlink behavior that affects docker and go builds, and the Rust people just reported something odd when building certain packages with mold). And yes, we've always handled -ENOSPC gracefully.
bombcar 1y ago
From my experience as a [x,z]fs snob, "further along than butterfs" is damning with faint praise.
bigyabai 1y ago
I have used BTRFS for 6 years on 5 drives without a single journaled corruption.
- pmarreck 1y ago
  And I used it for 2 years on 2 drives on 2 different OS'es (Manjaro and Arch) and had 2 corruptions that bricked the drives. And they were root filesystems, so... that wasn't fun. Statistics are funny like that.
  - taskforcegemini 1y ago
    bricked the drive as in the disk was physically defective? disks like to brick on their own, how sure are you btrfs was the reason?
int_19h 1y ago
btrfs is used by numerous NAS providers at this point.
- koverstreet 1y ago
  Do you know any that use it in multi device mode?
  - int_19h 1y ago
    Synology. (Yes, I know they don't do it "the right way". It still works at the end of the day.)
    - koverstreet 1y ago
      No, we're talking about btrfs multi device mode, md doesn't count :)
      - int_19h 1y ago
        Are we? You did not qualify your original statement about btrfs "not keeping data" with that.
pmarreck 1y ago
Hi, I believe I've contributed financially to your project in the past (mainly because zfs (licensing issues) and btrfs (unreliability, in my personal experience) need good competition... and btrfs bricked 2 of my drives once...) You've built an amazing thing but speaking as another very opinionated dev on the outside who sometimes butts heads with other opinionated devs- please just defer to Linus on this so you can get this in the kernel. Or just have it pushed to the next kernel release (I realize this has already happened repeatedly). Just please don't add a significant feature in a bugfix cycle. And (as mercurial as we all know he is, and as valid as some of your concerns surely are), try to keep the peace with that guy. Do it for the sake of the project. I've been waiting for this to drop for literally years now. I care about it, and I know no one does more than you, and I swear that I know exactly what that's like. It's your brain-baby, the concrete instantiation of your blood/sweat/tears. But... Take a deep breath, swallow, trust the process. The bands that produced some of the best music had HUGE tensions within them. But you can't let it explode (we all know that some bands did). I made that mistake a year ago, and lost a job I very much cared about. (Perhaps to a fault.) Don't be me. lol

we're further along than btrfs in "will it keep my data"

tremon 1y ago

Fair enough, I have no practical experience with bcachefs myself.

koverstreet 1y ago
Fair :) I've been trying to keep this thing (relatively) quiet and low profile until it's completely done, but it's gotten hyped. Data integrity, core IO paths, all the failure modes, all the crazy repair corner cases - these are the hard parts if you really want to get a filesystem right. These are what we've been taking our time on. I can't claim 100% success rate w.r.t. data loss, but it's been phenomenally good, with some crazy stories of filesystems we've gotten back that you'd never expect - and then it just becomes the norm. I love the crazy bug reports that really push the boundaries of our capabilities. That's an attitude that reiserfs and btrfs never had, and when I am confident that it is 100% rock solid and bulletproof I'll be lifting the experimental label.
sroussey 1y ago
> I have no practical experience with bcachefs myself. Who does? When the MySQL and Postgres projects recommend it, I’ll have a look.
- koverstreet 1y ago
  That's still a ways off, but it is worth noting that bcachefs handles database workloads in cow mode with no issue.

jcalvinowens 1y ago

> we're further along than btrfs in "will it keep my data" Honestly Kent, this continuing baseless fearmongering from you about btrfs is absolutely disgusting. It costs you. I was initially very interested in bcachefs, but I will never spend my time testing it or contributing to it as long as you continue behave this way. I'm certain there are many many others who would nominally be very interested, but feel the same way I do. Your filesystem charitably gets 0.001% the real world testing btrfs does. To claim it is more reliable than btrfs is ignorant and naive. Maybe it actually is more reliable in the real world (press X to doubt...), but you can't possibly know yet, and you won't know for a long time.

rob_c 1y ago
I'm happy to support that bcache may have a stable on disk format, but the lashing out at the alternatives is another example of behaviour I'd prefer to see dropped. If your product is so great its it's own advert. If it has problems spend the limited person power fixing it not attacking the opposition, this is what ciq have done, do better.
koverstreet 1y ago
We have documented, in this very thread, issues with multi device setups that btrfs has that bcachefs does not - and btrfs developers ignoring these issues. This isn't baseless fearmongering, this is "did you think through the failure modes when you were designing the basics". This stuff comes up over, and over, and over. Engineering things right matters, and part of that absolutely is comparing and documenting approaches and solutions to see what went right and what went wrong. This isn't a popularity contest, and this isn't high school where we form into cliques and start slinging insults. Come up with facts, documentation, analysis. That's what we do. I'm tired of these threads degenerating into flamewars.
- kzrdude 1y ago
  (That's impressive, but the real world user pool is much smaller isn't. It still sounds like a proud brag more than it does proven by workload.) I am not a filesystems guy, but I was disappointed when I realized that btrfs did not have a good design for ENOSPC handling. So I'm curious, does bcachefs design for a benign failure mode when out of space?
  - koverstreet 1y ago
    We have enough user reports of multi device testing that they put both bcachefs and btrfs through, where bcachefs consistently survives where btrfs does not. We have much better repair and recovery, with real defense in depth. Now: I am not saying that bcachefs is yet trouble free enough for widespread deployment, we're still seeing cases where repair needs fairly minor work, but the filesystem may be offline while we get that fixed. OTOH we also recover, regularly, from absolutely crazy scenarios involving hardware failure: flaky controllers, lightning strikes, I've seen cases where it looked like a head crashed - took out a whole bunch of btree nodes in similar LBA ranges. IOW: the fundamentals are very solid, but keep checking back if you're wondering when it'll be ready for widespread deployment. Milestones to watch for: - 3 months with zero data loss or downtime events: I think we may get this soon, knock on wood - stable backports starting: 6.17, knock on wood (or maybe we'll be out of the kernel and coming up with our own plan, who knows) - weird application specific bugs squashed: these have been on the back burner, but there's some weird stuff to get to still (e.g. weird unlink behavior that affects docker and go builds, and the Rust people just reported something odd when building certain packages with mold). And yes, we've always handled -ENOSPC gracefully.

bombcar 1y ago

From my experience as a [x,z]fs snob, "further along than butterfs" is damning with faint praise.

bigyabai 1y ago

I have used BTRFS for 6 years on 5 drives without a single journaled corruption.

pmarreck 1y ago
And I used it for 2 years on 2 drives on 2 different OS'es (Manjaro and Arch) and had 2 corruptions that bricked the drives. And they were root filesystems, so... that wasn't fun. Statistics are funny like that.
- taskforcegemini 1y ago
  bricked the drive as in the disk was physically defective? disks like to brick on their own, how sure are you btrfs was the reason?

int_19h 1y ago

btrfs is used by numerous NAS providers at this point.

koverstreet 1y ago
Do you know any that use it in multi device mode?
- int_19h 1y ago
  Synology. (Yes, I know they don't do it "the right way". It still works at the end of the day.)
  - koverstreet 1y ago
    No, we're talking about btrfs multi device mode, md doesn't count :)
    - int_19h 1y ago
      Are we? You did not qualify your original statement about btrfs "not keeping data" with that.

pmarreck 1y ago

Hi, I believe I've contributed financially to your project in the past (mainly because zfs (licensing issues) and btrfs (unreliability, in my personal experience) need good competition... and btrfs bricked 2 of my drives once...) You've built an amazing thing but speaking as another very opinionated dev on the outside who sometimes butts heads with other opinionated devs- please just defer to Linus on this so you can get this in the kernel. Or just have it pushed to the next kernel release (I realize this has already happened repeatedly). Just please don't add a significant feature in a bugfix cycle. And (as mercurial as we all know he is, and as valid as some of your concerns surely are), try to keep the peace with that guy. Do it for the sake of the project. I've been waiting for this to drop for literally years now. I care about it, and I know no one does more than you, and I swear that I know exactly what that's like. It's your brain-baby, the concrete instantiation of your blood/sweat/tears. But... Take a deep breath, swallow, trust the process. The bands that produced some of the best music had HUGE tensions within them. But you can't let it explode (we all know that some bands did). I made that mistake a year ago, and lost a job I very much cared about. (Perhaps to a fault.) Don't be me. lol