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Btrfs Allocator Hints

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Re: Btrfs Allocator Hints

#21

Post by pa7ch »

sandreas wrote: post #17

Well, first of all: I'm not trying to bash BTRFS at all, it probably is just not meant for me. However, I'm trying to gain information it is really considered stable (like rock solid) or it might have been a hardware Problem on my system. I used cryptsetup with BTRFS because I encrypt all of my stuff. One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). Not a real prob…

I worked on a linux distro some years ago that had to pull btrfs long after people had started saying thats its truly solid because customers had so many issues. Its probably improved since but its hard to know. Im surprised fedora workstation defaults to it now. I'm hoping bcachefs finds its way in the next few years as being the rock solid fs it aims to be.

Re: Btrfs Allocator Hints

#22

Post by fpoling »

sandreas wrote: post #17

Well, first of all: I'm not trying to bash BTRFS at all, it probably is just not meant for me. However, I'm trying to gain information it is really considered stable (like rock solid) or it might have been a hardware Problem on my system. I used cryptsetup with BTRFS because I encrypt all of my stuff. One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). Not a real prob…

Have you used 4K sectors with cryptsetup? Many distributions still defaults to 512 bytes if SSD reports 512 bytes as its logical size and with 512 sectors there are heavier load on the system.

I was reluctant to use BTRFS on my Linux laptop but for the last 3 years I have been using it with 4K cryptsetup with no issues.

Re: Btrfs Allocator Hints

#23

Post by piperswe »

ajross wrote: post #15
bayindirh wrote: post #14

Earlier quoted context omitted.

> You aren't doing that with ZFS or btrfs, though. ZFS can, and is actually designed to, handle that kind of workloads, though. At full configuration, ZFS7420 is a 84U configuration. Every disk box has its own set of "log" SSDs and 10 additional HDDs. Plus it was one of the rare systems which supported Infiniband access natively, and was able to saturate all of its Infiniband links under immense load. Lustre's perfor…

Again I think we're talking past each other. I'm saying "traditional filesystem-based storage management is not performance-limited at scale where everything is in RAM, so I don't see value to optimizations like that". You seem to be taking as a prior that at scale everything doesn't fit in RAM, so traditional filesystem-based storage management is still needed. But... everything does fit in RAM at scale. I mean, Clo…

Cloudflare's cache is a tiered cache with RAM and SSDs, not just RAM.

source: https://blog.cloudflare.com/why-we-started-putting-unpopular...

> Our storage layer, which serves millions of cache hits per second globally, is powered by high IOPS NVMe SSDs.

Re: Btrfs Allocator Hints

#24

Post by sandreas »

fpoling wrote: post #22
sandreas wrote: post #17

Well, first of all: I'm not trying to bash BTRFS at all, it probably is just not meant for me. However, I'm trying to gain information it is really considered stable (like rock solid) or it might have been a hardware Problem on my system. I used cryptsetup with BTRFS because I encrypt all of my stuff. One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). Not a real prob…

Have you used 4K sectors with cryptsetup? Many distributions still defaults to 512 bytes if SSD reports 512 bytes as its logical size and with 512 sectors there are heavier load on the system. I was reluctant to use BTRFS on my Linux laptop but for the last 3 years I have been using it with 4K cryptsetup with no issues.

I used the default archinstall... did not check the sector size, but good to hear it works for you. Maybe I'll check again with my next setup.

Re: Btrfs Allocator Hints

#25

Post by sandreas »

pa7ch wrote: post #21
sandreas wrote: post #17

Well, first of all: I'm not trying to bash BTRFS at all, it probably is just not meant for me. However, I'm trying to gain information it is really considered stable (like rock solid) or it might have been a hardware Problem on my system. I used cryptsetup with BTRFS because I encrypt all of my stuff. One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). Not a real prob…

I worked on a linux distro some years ago that had to pull btrfs long after people had started saying thats its truly solid because customers had so many issues. Its probably improved since but its hard to know. Im surprised fedora workstation defaults to it now. I'm hoping bcachefs finds its way in the next few years as being the rock solid fs it aims to be.

Yeah what really made me wonder is that I thought I had incomplete and wrong manpages in the recovery sections... examples did not work as described, but I can't remember what it was, I was too mad and ditched it completely :-)

Re: Btrfs Allocator Hints

#26

Post by sandreas »

ghostly_s wrote: post #18
sandreas wrote: post #17

Well, first of all: I'm not trying to bash BTRFS at all, it probably is just not meant for me. However, I'm trying to gain information it is really considered stable (like rock solid) or it might have been a hardware Problem on my system. I used cryptsetup with BTRFS because I encrypt all of my stuff. One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). Not a real prob…

Yes, my story with btrfs is quite similar- used it for a couple years, suddenly threw some undocumented error and refused to mount, asked about it on the dev irc channel and was told apparently it was a known issue with no solution, have fun rebuilding from backups. No suggestion that anyone was interested in documenting this issue, let alone fixing it. These same people are the only ones in the world suggesting btrf…

Ok, thank you. At least I'm not alone with this. However, I'm not too much into it and would not go as far to say it's not a recommendable project, but boy was I mad it just died without any way to recover ANYTHING :-)

Re: Btrfs Allocator Hints

#27

Post by sandreas »

riku_iki wrote: post #19
sandreas wrote: post #17

Well, first of all: I'm not trying to bash BTRFS at all, it probably is just not meant for me. However, I'm trying to gain information it is really considered stable (like rock solid) or it might have been a hardware Problem on my system. I used cryptsetup with BTRFS because I encrypt all of my stuff. One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). Not a real prob…

> One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). it looks like you didn't use raid, so any FS could fail in case of disk corruption.

Thank you for your opinion. Well... it did not just fail. Cryptsetup mounted everything fine, but the BTRFS tools did not find a valid filesystem on it.

While it could have been a bit flip that destroyed the whole encryption layer, BTRFS debugging revealed that there was some traces of BTRFS headers after mounting cryptsetup and some of the data on the decrypted partition was there...

This probably means the encryption layer was fine. The BTRFS part just could not be repaired or restored. The only explanation I have for this that something resulted in a dirty write, which destroyed the whole partition table, the backup partition table and since I used subvolumes and could not restore anything, most of the data.

Well, maybe it was my fault but since I'm using the exact same system with the same hardware right now (same NVMe SSD), I really doubt that.

Re: Btrfs Allocator Hints

#28

Post by riku_iki »

sandreas wrote: post #27
riku_iki wrote: post #19

Earlier quoted context omitted.

> One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). it looks like you didn't use raid, so any FS could fail in case of disk corruption.

Thank you for your opinion. Well... it did not just fail. Cryptsetup mounted everything fine, but the BTRFS tools did not find a valid filesystem on it. While it could have been a bit flip that destroyed the whole encryption layer, BTRFS debugging revealed that there was some traces of BTRFS headers after mounting cryptsetup and some of the data on the decrypted partition was there... This probably means the encrypti…

> Well, maybe it was my fault but since I'm using the exact same system with the same hardware right now (same NVMe SSD), I really doubt that.

anecdotes could be exchanged in both directions: I run heavy data processing with max possible throughput on top of btrfs raid for 10 years already, and never had any data loss. I am absolutely certain if you expect data integrity while relying on single disk: it is your fault.

Re: Btrfs Allocator Hints

#29

Post by ahofmann »

riku_iki wrote: post #19
sandreas wrote: post #17

Well, first of all: I'm not trying to bash BTRFS at all, it probably is just not meant for me. However, I'm trying to gain information it is really considered stable (like rock solid) or it might have been a hardware Problem on my system. I used cryptsetup with BTRFS because I encrypt all of my stuff. One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). Not a real prob…

> One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). it looks like you didn't use raid, so any FS could fail in case of disk corruption.

What the hell are you talking about? Any filesystem on any OS I've seen the last 3 decades had some kind of recovery path after any crash. Some of them lose more data, some of them less. But being unable to mount, is a bug that makes a filesystem untrustworthy and useless.

And how would RAID help in that situation?

Re: Btrfs Allocator Hints

#30

Post by riku_iki »

ahofmann wrote: post #29
riku_iki wrote: post #19

Earlier quoted context omitted.

> One day, the system froze and after reboot the partition was unrecoverably gone (the whole story[1]). it looks like you didn't use raid, so any FS could fail in case of disk corruption.

What the hell are you talking about? Any filesystem on any OS I've seen the last 3 decades had some kind of recovery path after any crash. Some of them lose more data, some of them less. But being unable to mount, is a bug that makes a filesystem untrustworthy and useless. And how would RAID help in that situation?

> But being unable to mount, is a bug that makes a filesystem untrustworthy and useless.

we are in disagreement on this. If partition table entry corrupted, you can't mount without some low level surgery.

> And how would RAID help in that situation?

depending on raid, your data will be duplicated on another disk, and will survive in case of one/few disks corruption.

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