> In legal usage throughout the English-speaking world, an act of God is a natural hazard outside human control, such as an earthquake or tsunami, for which no person can be held responsible.
> In the law of torts, an act of God may be asserted as a type of intervening cause, the lack of which would have avoided the cause or diminished the result of liability (e.g., but for the earthquake, the old, poorly constructed building would be standing). However, foreseeable results of unforeseeable causes may still raise liability. For example, a bolt of lightning strikes a ship carrying volatile compressed gas, resulting in the expected explosion. Liability may be found if the carrier did not use reasonable care to protect against sparks—regardless of their origins. Similarly, strict liability could defeat a defense for an act of God where the defendant has created the conditions under which any accident would result in harm. For example, a long-haul truck driver takes a shortcut on a back road and the load is lost when the road is destroyed in an unforeseen flood.
Kent has admitted (many times) that snapshots are one of the more difficult features to add in a reliable and safe way, and will require significant work to do right, especially for what he wants to see them do (I assume "really damn fast and low overhead" is a major one, plus some other tricks he has up his sleeve.) So he has intentionally not tackled them yet, instead going after a slew of other features first. Reflink, full checksum, replication, caching, compression, native encryption, etc. All of that works today.
Snapshots are a huge feature for sure, but it's not like bcachefs is completely incapable without them.
There was a very recent update he gave in late December (2019) that mentioned he's actively chipping away at the roadblocks for snapshots.
They're being worked on ATM:
Dec 29, 2019
"Just finished a major rework that gets us a step closer to snapshots: the btree code is incrementally being changed to handle extents like regular keys."
https://www.patreon.com/posts/towards-32698961
Heh, BTRFS deja vu. Been hearing about the ZFS alternative "not quite there, but catching up" for about as long as high-speed rail. I wonder which will arrive first :)
BTRFS is never going to become stable. Ever. Just take a quick dive into the codebase.
Bcachefs has never had an unrecoverable data error AFAIK, even though it isn't even considered stable enough to merge into the kernel. The bcache on disk format won't be considered stable until he merges his code into mainline, though he doesn't feel he will need to adjust it further.
Features that currently work:
Full data checksumming
Compression
Multiple device support
Tiering/writeback caching
RAID1/RAID10
All of these are stable, tested, and mostly bug free. Honestly, once the code gets mainlined you'll be able to start using it very quickly.
Main issue right now is performance, as it about as slow as BTRFS, which isn't inspiring. However the author has stated that he's going for correctness first, then he'll begin optimizing.
It's not a bug, but an unimplemented feature. They never made any promise that raid5 is production-ready.
Pretty much all software-raid systems suffer from it unless they explicitly patch over it via journaling. Hardware raid gets away with it if it has battery backups, if they don't they suffer from exactly the same problem.
My home NAS runs btrfs in RAID 5. The key is to use software RAID / LVM to present a single block device to btrfs. That way you never use btrfs's screwed-up RAID 5/6 implementation.
That's a good point, though Synology (my brand of NAS) claims that they've developed analogous corruption checks operating at the LVM level, so you get the benefits of btrfs (including checksum checks and RAID scrubbing) without having to actually use its RAID implementation.
I wasn't actually able to find any real documentation on how Synology's SHR works.
Their recovery documentation [0] indicates that SHR is just plain mdadm + LVM and a couple of NAS recovery sites [1,2] indicate the same.
In the end I got a Reddit post [3] with a response from a Synology representative who says that the btrfs filesystem will request a read from a redundant copy from mdadm in order to correct checksum errors.
I wonder whether this is unique to Synology or whether the change has been upstreamed into the main Linux kernel.
Why use RAID5/6, RAID10 is much more safe because you drastically reduce the change of a cascading resilvering failure. Yes, you get less capacity per drive, but drives are (relatively) cheap.
I thought I wanted RAID5, but after reading horror stories of drives failing when replacing a failed drive, I decided it just wasn't worth the risk.
I currently run RAID1, and when I need more space, I'll double my drives and set up RAID10. I don't need most of the features of ZFS, so BTRFS works for me.
I use RAID6 because it gives me highly efficient utilization of my available storage capacity while still giving me some degree of redundancy should a disk fail. My workload is also mostly sequential, so random read/write performance isn't too important to me.
If a disk fails and resilvering causes a cascading failure, I can restore from a backup.
I think you might be mistaking RAID for a backup, which is a mistake. RAID is very much not a backup or any kind of substitute for a backup. A backup ensures durability and integrity of your data by providing an independent fallback should your primary storage fail. RAID ensures availability of your data by keeping your storage online when up to N disks fail.
RAID won't protect you from an accidental "rm -Rf /", ransomware or other malware, bugs in your software or many other common causes of data loss.
I might consider RAID10 if I were running a business-critical server where availability was paramount, or where I needed decent random read/write performance but even so I'd still want a hot-failover and a comprehensively tested backup strategy.
btrfs is not at all reliable, so if you care about your files staying working files, it probably doesn't meet your requirements. It is like the MongoDB 0.1 of filesystems.
When it comes to file systems “pretty reliable” these days does not sound very good. Reliability had to have been a fundamental requirement for design of a file system. If not, it sounds like putting lipstick on a pig.
Redhat throwing towel on their support for development does not instill confidence either.
Nothing personally against Btrfs. Just an end user making a file system choice saying what I care about.
> People are making a bigger deal of this than it is. Since I left Red Hat in 2012 there hasn't been another engineer to pick up the work, and it is _a lot_ of work.
Game Tools on Samsung devices have this feature. For apps that aren't games you need to add them in Game Launcher so the Game Tools button appears in those apps.
At the low end, in Chromebooks, I think Arm processors are a better way to go. These days Chromebooks run Android apps and Android on x86 hasn't been great.
Gemini Lake is really good in the $250 to $350 segment. They have great hardware video decoding/encoding and the general CPU performance is between Core2 and Nehalem level, while offering Chromebook level battery life.
There are Chinese laptops like the Chuwui Lapbook Pro that get you a 1080p IPS screen, a quad-core Gemini Lake, and 8G of RAM for $320. I'd rather do that and be able to run standard x86 software at semi-reasonable speed than to mess with a chromebook. (I can see the draw for a momputer that you don't want to mess with though)
I'd love something in the 7nm or 10nm class, of course. If Dali was on Zen2 on 7nm it would be fantastic. It's just not possible yet in this price range. AMD is still launching 14nm in this segment, not even Zen+. Next-gen Atom (Skyhawk Lake) is going to be on Intel 14nm as well.
I'm curious how Dali/Barred Kestrel does on the extreme battery life/chromebook thing though. Raven Ridge (and the Zen+ successor, Picasso) did not have great idle power and this hurt it there. If they could get the idle power down, it would be a good alternative to Gemini Lake.
In many segments, low-end included, the processor is a small part of the total BoM. Display, memory, clamshell, keyboard, assembly and shipping are non-negligible.
One of the fun things about ARM is that you get to play with asymmetric multicore machines that don't exist anywhere else in the desktop space. At least for now.
For me, the worst flaw of Chromebooks is the keyboard and the lack of proper Control, Super and Meta keys.
https://scholarship.law.upenn.edu/cgi/viewcontent.cgi?articl...
https://en.wikipedia.org/wiki/Animal_trial