Linux Storage, Filesystem, and Memory-Management Summit

https://lwn.net/Articles/lsfmm2019/

by l2dy • 7 years ago

148 56 7 years ago

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topspin• 7 years ago

Btrfs isn't even on the agenda.

asymmetric• 7 years ago

Your point being?

lifty• 7 years ago

It would have been nice if btrfs would be discussed, since it's supposed to be the next generation filesystem for Linux.

est312• 7 years 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.

foobiekr3• 7 years 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

LeoPanthera• 7 years 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.

josefbacik2• 7 years ago

Not sure what you are talking about, it’s definitely endian neutral. You can’t take different page sized fs and put it on another page size arch, but that’s a separate issue.

guywhocodes• 7 years ago

Wow did we work on the same startup? We ended up with a ZoL cluster with better but not great stability instead with less than half the performance for latency critical loads. But at least it was correct.

osandov• 7 years 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.

josefbacik2• 7 years 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• 7 years ago

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

corbet2• 7 years ago

No video recording was done, so no.

philips• 7 years 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• 7 years 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• 7 years 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/)

gumby2• 7 years 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• 7 years 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/

2: http://docs.ceph.com/docs/master/radosgw/nfs/

kevin_thibedeau• 7 years ago

I use NFS for a media/backup server since I don't want to bother with Samba.

HankB99• 7 years 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• 7 years 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.

happythought2• 7 years 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.

muxator• 7 years ago

Yes, it has now been replaced by Gitaly: https://about.gitlab.com/2018/09/12/the-road-to-gitaly-1-0/

zaphirplane• 7 years ago

VMware over NFS maybe used in SMB (small medium businesses) enterprises use iscsi or SANs

when the NFS server crashes bad things happen and if you are building a redundant multi master NFS it’s a lot simpler to use iscsi and FC SAN

ajdlinux• 7 years ago

NFS is absolutely still in use at my workplace - there's a lot of older infrastructure still in place that makes use of it. Lots of AFS as well.

I believe my alma mater's CS department is still using NFS for home directories last I checked.

arminiusreturns• 7 years ago

Yep, it is still widely used as smb/cifs is a horrible protocol and it should feel bad.

There are some issues with nfs(v4) on the bleeding edge by default, but it has been really cool to see some of the nfs workarounds to deal with big data.

6keZbCECT2uB• 7 years ago

My bias shows here, but what's your alternative to NFS from *nix? We used AFS at school. I suppose you could keep your data locally and be responsible for your own backups / use version control as backups.

beagle32• 7 years ago

CIFS / SMB ; Client is in most kernels these days, server (Samba) is easy to install and use. In my experience performance is acceptable (that is, I'm getting >110MB/s on a 1Gb connection), locking semantics if you need them work much better than an NFS - and most importantly, it doesn't hang as bad when a server goes away (NFS behaves like it's 1980 in that respect - the recommended and only consistent way to unhang processes when the server goes away is, I kid you not, start a local NFS server on the client, and add the IP address of the server locally to the client; Then, one of the retries will get an error from the local server, at that point you can deal with it, shutdown the local NFS and remove the extra IP address)

simula67• 7 years ago

I used to work for a hyper converged infrastructure provider which had an option to aggregate all the disks in a computing cluster and expose it as an NFS filesystem. You can then enable fault tolerance, compression, encryption etc on a file system level.

pfranz3• 7 years ago

I'm curious what your domain is and what tech you've been using?

Every Linux shop I've worked in 10+ years has used NFS without any word of an alternative. The few places I've worked that mixed NFS with SMB or exclusively used SMB I've had performance issues when jumping between the two (perhaps due to experience and configuration).

My work has mostly been in Linux shops with 10s-100s of workstations+servers. NFS was used for homedirs and shared data. Sometimes servers were hundreds of miles away.

gumby2• 7 years ago

I'm curious what your domain is and what tech you've been using?

It’s good to see these replies as everybody’s experience is different and I learn by asking.

Perhaps NFS has improved a lot; I started using it in the 1980s after using client/server filesystems like IFS and Alpine at parc and the per-file protocols we had at mit for the pod-10s and Lispms. With NFS locking and such were painful because it tried hard to look no different from a local filesystem, but couldn’t be. Network mounted homedirs were common to me from the early 80s but under NFS were too painful.

I imagine things have improved over the last couple of decades!

The environments I’ve used more recently have used a combination of replication (e.g. Dropbox), moved the computation to the data (“cloud” though for me typically this has meant in-house someplace rather than a third party or shared machine) or hybrid (e.g. IMAP).

Datasets tend not to be super huge — < 50 TB — so other approaches are used at the back end.

reacharavindh• 7 years ago

HPC sysadmin here. Our cluster is built around NFS for storage. User home directories are mounted on all compute nodes via NFS. Research datasets are mounted on compute nodes via NFS. It is simple and stable and works very well within our internal network.

notacoward• 7 years ago

NFS is increasingly becoming an access protocol, to speak to $whatever through some sort of proxy/gateway. $whatever might be Gluster (for which I'm still a maintainer), Ceph, EFS, etc. It's nice because clients are everywhere, they're maintained by someone else, and you can update your own stuff as much as you like without landing in the swamp of updating client software. The people who do maintain those clients - I know a few - deserve our thanks.

corbet2• 7 years ago

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Linux Storage, Filesystem, and Memory-Management Summit

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