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Linux Storage, Filesystem, and Memory-Management Summit

148 points by l2dy 7y ago

topspin 7y ago
Btrfs isn't even on the agenda.
- asymmetric 7y ago
  Your point being?
  - lifty 7y ago
    It would have been nice if btrfs would be discussed, since it's supposed to be the next generation filesystem for Linux.
    - jstimpfle 7y ago
      since... 10 years soon?
  - est31 7y ago
    Neither btrfs or the newer bcachefs being on that page is kinda sad as Linux is supposed to be the #1 operating system / kernel and Apple has deployed a next-gen file system by default but in the Linux world nothing seems to be happening beyond some people who still believe that btrfs has a future and one guy who is implementing bcachefs and has to beg for money on patreon because apparently no company wants to hire him to work on it. In many ways ext4 is "good enough" but there are sweed juicy advantages of copy on write, checksummed file systems. I guess all of the enthusiasts are using ZFS which is a work of art but it has licensing problems AND IP is owned by a law firm with some engineers attached that was kickstarted by the CIA.
    - koverstreet 7y ago
      I felt like I had too much going on at the time when conference proposals were going out to attend, so that's why bcachefs isn't mentioned. But that's not for lack of progress; upstreaming is actually getting really close.
      - est31 7y ago
        Wow, that's amazing. Looking forward to it!
    - 99052882514569 7y ago
      I don't think ZoL[1], a based on a ground-up re-implementation of ZFS, has those licensing/IP issues. We've been using it in production problem free for a year now (on Ubuntu 18). [1] https://zfsonlinux.org/ https://zfsonlinux.org/
      - justinsaccount 7y ago
        > ZoL[1], a based on a ground-up re-implementation of ZFS ZFS on linux is not a re-implementation of ZFS
      - yjftsjthsd-h 7y ago
        ZoL is a port, not a reimplementation at all, and retains all of the licensing problems. Ubuntu ships it because they have a different reading of the licensing situation than many involved parties.
    - asveikau 7y ago
      > IP is owned by a law firm with some engineers attached that was kickstarted by the CIA. I use ZFS and know a bit of the history, but it took me a while to realize that meant "Oracle". I didn't realize CIA was their first customer (something I found while googling just now) but I suppose that's not too surprising. Although to be fair I am not sure having CIA as a client in 1977 means much for ZFS.
    - m4rtink 7y ago
      A lot is happening arround XFS, LVM, device mapper and also the Stratis project. Also a thin LV with XFS will give you many if not most of the benefits of BTRFs/ZFS but with stability and being available on any reasonably old Linux distro.
- foobiekr 7y ago
  is btrfs as a project even healthy? a startup I worked at looked hard at btrfs since the COW model and better integrity verification were both very, very useful from our POV. But btrfs in practice was just simply unsuitable; not only were there basic reliability issues (corrupted filesystems) and really bad corner case behavior (full filesystem in particular), we noted that it was not actually fully endian neutral, at least at the time, which caused filesystems between x86 and a BE ISA to appear to work, and then to be horribly corrupted if taken from a BE embedded system and mounted on x86. Given the volume of btrfs negative experiences that are going to need to be overcome (for example, many of the posts in [1]), maybe people have just given up? If ZoL licensing wasn't a problem, would anyone even be interested? [1] https://news.ycombinator.com/item?id=15087754 https://news.ycombinator.com/item?id=15087754
  - LeoPanthera 7y ago
    I routinely hear about how btrfs is unreliable, unstable, and corrupts your data. But it's also been the default filesystem for SUSE Linux and Synology NAS products for a long time now, and they don't seem to be having any problems. I don't know what to believe.
    - Leace 7y ago
      I'm using btrfs for a year on my laptop and there are no problems. I did some research before as I considered ZFS too but it seems most btrfs criticism is from old versions that did have bugs or using configurations that have known flaws (raid5/6, see [0]). ZFS, as much as I like it, will unfortunately never be part of the kernel and users will constantly be put into this kind of situations: https://www.phoronix.com/scan.php?page=news_item&px=ZFS-On-Linux-5.0-Problem https://www.phoronix.com/scan.php?page=news_item&px=ZFS-On-L... [0]: https://btrfs.wiki.kernel.org/index.php/Gotchas https://btrfs.wiki.kernel.org/index.php/Gotchas
    - berkut 7y ago
      ReadyNAS products have also been using it for even longer. They don't use the RAID support from BTRFS (they do it themselves in software a level up using mdadm), only the snapshot, COW and general storage. There very occasionally (based on forum posts) seem to be issues with metadata fragmentation for some people when there's a lot of metadata, but otherwise seems very reliable (I've got two myself).
- osandov 7y ago
  The filesystem track at LSF/MM tends to focus on topics which impact more of the kernel than one specific filesystem, and we didn't have any of those topics for Btrfs this year. Plus, only a couple of the Btrfs developers were at LSF/MM this year, and we typically sync up via other means.
- josefbacik 7y ago
  Cause it’s a summit to talk about the whole ecosystem, not one file system. We btrfs developers talk enough to each other, we don’t need to bore the rest of the attendees with our own topics. That’s what the hallway tracks are for. I put together the schedule for the file system side of this years conference, I specifically don’t put single fs issues on the general schedule.
navidr 7y ago
Are videos of this conference available or is going to be available?
- corbet 7y ago
  No video recording was done, so no.
philips 7y ago
Favorite quote from the articles so far about BPF: Gregg started with a demonstration tool that he had just written: it's immediate manifestation was in the creation of a high-pitched tone that varied in frequency as he walked around the lectern. It was, it turns out, a BPF-based tool that extracts the signal strength of the laptop's WiFi connection from the kernel and creates a noise in response. As he interfered with that signal with his body, the strength (and thus the pitch of the tone) varied. By tethering the laptop to his phone, he used the tool to measure how close he was to the laptop. It may not be the most practical tool, but it did demonstrate how BPF can be used to do unexpected things.
- bionsystem 7y ago
  Brendan Gregg is also the guy who shouted at a rack in a datacenter to prove that some hard drives were sensitive performance-wise to vibrations. The video is on youtube and it's hilarious.
htfy96 7y ago
> System observability with BPF Initially I thought this was about recent Spectre vulnerability variants related to BPF. Then I found it is actually discussed in BPF: what's good, what's coming, and what's needed (https://lwn.net/Articles/787856/ https://lwn.net/Articles/787856/)
gumby 7y ago
I was surprised to see discussion of NFS. NFS certainly was a big deal "back in the day" but it had its own quirks and headaches. I haven't seen NFS in 20 years, but that could simply be because of the particular worlds I live in. Is it still widely used and I just happen never to see it because the environments in which I work? Or is it only used for a small number of sites (or certain applications) but they happen to be extremely important ones?
- inyorgroove 7y ago
  AWS EFS[1] uses NFS which our team used last year for some internal infrastructure. NFS is still around. Also have been looking into more durable storage this year it looks like the Rados gateway[2] in Ceph supports a nfs front end as well. 1: https://aws.amazon.com/efs/ https://aws.amazon.com/efs/ 2: http://docs.ceph.com/docs/master/radosgw/nfs/ http://docs.ceph.com/docs/master/radosgw/nfs/
- kevin_thibedeau 7y ago
  I use NFS for a media/backup server since I don't want to bother with Samba.
- HankB99 7y ago
  I was surprised more because I thought it was pretty well settled. I use it in my home LAN to access file shares. (Linux desktops and a Linux server.) Is would be used between 'nix servers and clients? Is it something that would be useful on the home LAN?
- tw04 7y ago
  I would be shocked if there's a single fortune 500 that doesn't have a significant NFS footprint. Everything from user shares to Oracle or VMware get deployed via NFS.
- happythought 7y ago
  VMware supports NFS as a storage backend so it ends up being used in a lot of storage arrays in Enterprise shops. Gitlab.com was also using it as of last year, but I’m not sure if that’s still the case.
corbet 7y ago
If you appreciate this kind of reporting, please consider subscribing to LWN. Subscriber support is the only thing that allows us to do this kind of work.
stevehiehn 7y ago
Jeez, the gender ratio in that pic is note worthy: https://lwn.net/Articles/787191/ https://lwn.net/Articles/787191/

148 points by l2dy 7y ago

topspin 7y ago

Btrfs isn't even on the agenda.

asymmetric 7y ago
Your point being?
- lifty 7y ago
  It would have been nice if btrfs would be discussed, since it's supposed to be the next generation filesystem for Linux.
  - jstimpfle 7y ago
    since... 10 years soon?
- est31 7y ago
  Neither btrfs or the newer bcachefs being on that page is kinda sad as Linux is supposed to be the #1 operating system / kernel and Apple has deployed a next-gen file system by default but in the Linux world nothing seems to be happening beyond some people who still believe that btrfs has a future and one guy who is implementing bcachefs and has to beg for money on patreon because apparently no company wants to hire him to work on it. In many ways ext4 is "good enough" but there are sweed juicy advantages of copy on write, checksummed file systems. I guess all of the enthusiasts are using ZFS which is a work of art but it has licensing problems AND IP is owned by a law firm with some engineers attached that was kickstarted by the CIA.
  - koverstreet 7y ago
    I felt like I had too much going on at the time when conference proposals were going out to attend, so that's why bcachefs isn't mentioned. But that's not for lack of progress; upstreaming is actually getting really close.
    - est31 7y ago
      Wow, that's amazing. Looking forward to it!
  - 99052882514569 7y ago
    I don't think ZoL[1], a based on a ground-up re-implementation of ZFS, has those licensing/IP issues. We've been using it in production problem free for a year now (on Ubuntu 18). [1] https://zfsonlinux.org/ https://zfsonlinux.org/
    - justinsaccount 7y ago
      > ZoL[1], a based on a ground-up re-implementation of ZFS ZFS on linux is not a re-implementation of ZFS
    - yjftsjthsd-h 7y ago
      ZoL is a port, not a reimplementation at all, and retains all of the licensing problems. Ubuntu ships it because they have a different reading of the licensing situation than many involved parties.
  - asveikau 7y ago
    > IP is owned by a law firm with some engineers attached that was kickstarted by the CIA. I use ZFS and know a bit of the history, but it took me a while to realize that meant "Oracle". I didn't realize CIA was their first customer (something I found while googling just now) but I suppose that's not too surprising. Although to be fair I am not sure having CIA as a client in 1977 means much for ZFS.
  - m4rtink 7y ago
    A lot is happening arround XFS, LVM, device mapper and also the Stratis project. Also a thin LV with XFS will give you many if not most of the benefits of BTRFs/ZFS but with stability and being available on any reasonably old Linux distro.
foobiekr 7y ago
is btrfs as a project even healthy? a startup I worked at looked hard at btrfs since the COW model and better integrity verification were both very, very useful from our POV. But btrfs in practice was just simply unsuitable; not only were there basic reliability issues (corrupted filesystems) and really bad corner case behavior (full filesystem in particular), we noted that it was not actually fully endian neutral, at least at the time, which caused filesystems between x86 and a BE ISA to appear to work, and then to be horribly corrupted if taken from a BE embedded system and mounted on x86. Given the volume of btrfs negative experiences that are going to need to be overcome (for example, many of the posts in [1]), maybe people have just given up? If ZoL licensing wasn't a problem, would anyone even be interested? [1] https://news.ycombinator.com/item?id=15087754 https://news.ycombinator.com/item?id=15087754
- LeoPanthera 7y ago
  I routinely hear about how btrfs is unreliable, unstable, and corrupts your data. But it's also been the default filesystem for SUSE Linux and Synology NAS products for a long time now, and they don't seem to be having any problems. I don't know what to believe.
  - Leace 7y ago
    I'm using btrfs for a year on my laptop and there are no problems. I did some research before as I considered ZFS too but it seems most btrfs criticism is from old versions that did have bugs or using configurations that have known flaws (raid5/6, see [0]). ZFS, as much as I like it, will unfortunately never be part of the kernel and users will constantly be put into this kind of situations: https://www.phoronix.com/scan.php?page=news_item&px=ZFS-On-Linux-5.0-Problem https://www.phoronix.com/scan.php?page=news_item&px=ZFS-On-L... [0]: https://btrfs.wiki.kernel.org/index.php/Gotchas https://btrfs.wiki.kernel.org/index.php/Gotchas
  - berkut 7y ago
    ReadyNAS products have also been using it for even longer. They don't use the RAID support from BTRFS (they do it themselves in software a level up using mdadm), only the snapshot, COW and general storage. There very occasionally (based on forum posts) seem to be issues with metadata fragmentation for some people when there's a lot of metadata, but otherwise seems very reliable (I've got two myself).
osandov 7y ago
The filesystem track at LSF/MM tends to focus on topics which impact more of the kernel than one specific filesystem, and we didn't have any of those topics for Btrfs this year. Plus, only a couple of the Btrfs developers were at LSF/MM this year, and we typically sync up via other means.
josefbacik 7y ago
Cause it’s a summit to talk about the whole ecosystem, not one file system. We btrfs developers talk enough to each other, we don’t need to bore the rest of the attendees with our own topics. That’s what the hallway tracks are for. I put together the schedule for the file system side of this years conference, I specifically don’t put single fs issues on the general schedule.

navidr 7y ago

Are videos of this conference available or is going to be available?

corbet 7y ago
No video recording was done, so no.

philips 7y ago

Favorite quote from the articles so far about BPF: Gregg started with a demonstration tool that he had just written: it's immediate manifestation was in the creation of a high-pitched tone that varied in frequency as he walked around the lectern. It was, it turns out, a BPF-based tool that extracts the signal strength of the laptop's WiFi connection from the kernel and creates a noise in response. As he interfered with that signal with his body, the strength (and thus the pitch of the tone) varied. By tethering the laptop to his phone, he used the tool to measure how close he was to the laptop. It may not be the most practical tool, but it did demonstrate how BPF can be used to do unexpected things.

bionsystem 7y ago
Brendan Gregg is also the guy who shouted at a rack in a datacenter to prove that some hard drives were sensitive performance-wise to vibrations. The video is on youtube and it's hilarious.

htfy96 7y ago

> System observability with BPF Initially I thought this was about recent Spectre vulnerability variants related to BPF. Then I found it is actually discussed in BPF: what's good, what's coming, and what's needed (https://lwn.net/Articles/787856/ https://lwn.net/Articles/787856/)

gumby 7y ago

I was surprised to see discussion of NFS. NFS certainly was a big deal "back in the day" but it had its own quirks and headaches. I haven't seen NFS in 20 years, but that could simply be because of the particular worlds I live in. Is it still widely used and I just happen never to see it because the environments in which I work? Or is it only used for a small number of sites (or certain applications) but they happen to be extremely important ones?

inyorgroove 7y ago
AWS EFS[1] uses NFS which our team used last year for some internal infrastructure. NFS is still around. Also have been looking into more durable storage this year it looks like the Rados gateway[2] in Ceph supports a nfs front end as well. 1: https://aws.amazon.com/efs/ https://aws.amazon.com/efs/ 2: http://docs.ceph.com/docs/master/radosgw/nfs/ http://docs.ceph.com/docs/master/radosgw/nfs/
kevin_thibedeau 7y ago
I use NFS for a media/backup server since I don't want to bother with Samba.
HankB99 7y ago
I was surprised more because I thought it was pretty well settled. I use it in my home LAN to access file shares. (Linux desktops and a Linux server.) Is would be used between 'nix servers and clients? Is it something that would be useful on the home LAN?
tw04 7y ago
I would be shocked if there's a single fortune 500 that doesn't have a significant NFS footprint. Everything from user shares to Oracle or VMware get deployed via NFS.
happythought 7y ago
VMware supports NFS as a storage backend so it ends up being used in a lot of storage arrays in Enterprise shops. Gitlab.com was also using it as of last year, but I’m not sure if that’s still the case.

corbet 7y ago

If you appreciate this kind of reporting, please consider subscribing to LWN. Subscriber support is the only thing that allows us to do this kind of work.

stevehiehn 7y ago

Jeez, the gender ratio in that pic is note worthy: https://lwn.net/Articles/787191/ https://lwn.net/Articles/787191/