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ZFS: Apple's new filesystem that wasn't (2016)

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Re: ZFS: Apple's new filesystem that wasn't (2016)

#71
post #2

Besides the licensing issue, I wonder if optimizing ZFS for low latency + low RAM + low power on iPhone was an uphill battle or if it’s easy. My experiencing running ZFS years ago was poor latency and large RAM use with my NAS, but that hardware and drive configuration was optimized for low $ per gb stored and used parity stuff.

Apple wanted one operating system that ran on everything from a Mac Pro to an Apple Watch and there’s no way ZFS could have done that.

Re: ZFS: Apple's new filesystem that wasn't (2016)

#72
post #31

Thanks for sharing I was just looking for what happened to Sun. I like the second-hand quote comparing the IBM and HP as "garbage trucks colliding" plus the inclusion of blog posts with links to the court filings. Is it fair to say ZFS made most sense on Solaris using Solaris Containers on SPARK?

ZFS was developed in Solaris, and at the time we were mostly selling SPARC systems. That changed rapidly and the biggest commercial push was in the form of the ZFS Storage Appliance that our team (known as Fishworks) built at Sun. Those systems were based on AMD servers that Sun was making at the time such as Thumper [1]. Also in 2016, Ubuntu leaned in to use of ZFS for containers [2]. There was nothing that specific…

Thanks. Also, the Thumper looks awesome like a max-level MMORPG character that would kill the level-1 consumer Synology NAS character in one hit.

Re: ZFS: Apple's new filesystem that wasn't (2016)

#73
post #26

I wonder what ZFS in the iPhone would've looked like. As far as I recall, the iPhone didn't have error correcting memory, and ZFS is notorious for corrupting itself when bit flips hit it and break the checksum on disk. ZFS' RAM-hungry nature would've also forced Apple to add more memory to their phone.

It's very amusing that this kind of legend has persisted! ZFS is notorious for *noticing* when bits flip, something APFS designers claimed was rare given the robustness of Apple hardware.[1][2] What would ZFS on iPhone have looked like? Hard to know, and that certainly wasn't the design center. Neither here nor there, but DTrace was ported to iPhone--it was shown to me in hushed tones in the back of an auditorium onc…

I did early ZFSOnLinux development on hardware that did not have ECC memory. I once had a situation where a bit flip happened in the ARC buffer for libpython.so and all python software started crashing. Initially, I thought I had hit some sort of blizzard bug in ZFS, so I started debugging. At that time, opening a ZFS snapshot would fetch a duplicate from disk into a redundant ARC buffer, so while debugging, I ran cmp on libpython.so between the live copy and a snapshot copy. It showed the exact bit that had flipped. After seeing that and convincing myself the bitflip was not actually on stable storage, I did a reboot, and all was well. Soon afterward, I got a new development machine that had ECC so that I would not waste my time chasing phantom bugs caused by bit flips.

Re: ZFS: Apple's new filesystem that wasn't (2016)

#74
post #34

Earlier quoted context omitted.

There is a rule of thumb that you should have at least 1 GB of RAM per TB of disk when using deduplication . That's.... Different.

So you've never seen the people saying you should steer clear of ZFS unless you're going to have an enormous ARC even when talking about personal media servers?

I have seen people say such things, and none of it was based on reality. They just misinterpreted the performance cliff that data deduplication had to mean you must have absurd amounts of memory even though data deduplication is off by default. I suspect few of the people peddling this nonsense even used ZFS and the few who did, had not looked very deeply into it.

Re: ZFS: Apple's new filesystem that wasn't (2016)

#75

The death of ZFS in macOS was a huge shift in the industry. This has to be seen in the context of microsoft killed their largely ambitious WinFS which felt like the death of desktop innovation in combination.

Both are imho linked to "offline desktop use cases are not important anymore". Both companies saw their future gains elsewhere, in internet-related functions and what became known as "cloud". No need to have a fancy, featurefull and expensive filesystem when it is only to be used as a cache for remote cloud stuff.

Internet connections of the day didn't yet offer enough speed for cloud storage.

Apple was already working to integrate ZFS when Oracle bought Sun.

From TFA:

> ZFS was featured in the keynotes, it was on the developer disc handed out to attendees, and it was even mentioned on the Mac OS X Server website. Apple had been working on its port since 2006 and now it was functional enough to be put on full display.

However, once Oracle bought Sun, the deal was off.

Again from TFA:

> The Apple-ZFS deal was brought for Larry Ellison's approval, the first-born child of the conquered land brought to be blessed by the new king. "I'll tell you about doing business with my best friend Steve Jobs," he apparently said, "I don't do business with my best friend Steve Jobs."

And that was the end.

Re: ZFS: Apple's new filesystem that wasn't (2016)

#76

As a desktop user, I am content with APFS. The only feature from ZFS that I would like, is the corruption detection. I honestly don't know how robust the image and video formats are to bit corruption. On the one hand, potentially, "very" robust. But on the other, I would think that there are some very special bits that if toggled can potentially "ruin" the entire file. But I don't know. However, I can say, every time…

> I honestly don't know how robust the image and video formats are to bit corruption.

It depends on the format. A BMP image format would limit the damage to 1 pixel, while a JPEG could propagate the damage to potentially the entire image. There is an example of a bitflip damaging a picture here:

https://arstechnica.com/information-technology/2014/01/bitro...

That single bit flip ruined about half of the image.

As for video, that depends on how far apart I frames are. Any damage from a bit flip would likely be isolated to the section of video from the bitflip until the next I-frame occurs. As for how bad it could be, it depends on how the encoding works.

> On the one hand, potentially, "very" robust.

Only in uncompressed files.

> But on the other, I would think that there are some very special bits that if toggled can potentially "ruin" the entire file. But I don't know.

The way that image compression works means that a single bit flip prior to decompression can affect a great many pixels, as shown at Ars Technica.

> However, I can say, every time I've tried ZFS on my iMac, it was simply a disaster.

Did you file an issue? I am not sure what the current status of the macOS driver’s production readiness is, but it will be difficult to see it improve if people do not report issues that they have.

Re: ZFS: Apple's new filesystem that wasn't (2016)

#77

As a desktop user, I am content with APFS. The only feature from ZFS that I would like, is the corruption detection. I honestly don't know how robust the image and video formats are to bit corruption. On the one hand, potentially, "very" robust. But on the other, I would think that there are some very special bits that if toggled can potentially "ruin" the entire file. But I don't know. However, I can say, every time…

> Just trying to set it up on a single USB drive

That's the fault of macOS, I also experienced 100% CPU and load off the charts and it was kernel_task jammed up by USB. Once I used a Thunderbolt enclosure it started to be sane. This experience was the same across multiple non-Apple filesystems as I was trying a bunch to see which one was the best at cross-os compatibility

Also, separately, ZFS says "don't run ZFS on USB". I didn't have problems with it, but I knew I was rolling the dice

Re: ZFS: Apple's new filesystem that wasn't (2016)

#78
post #65
post #45

Earlier quoted context omitted.

But SSDs (to my knowledge) only implement checksum for the data transfer. Its a requirement of the protocol. So you can be sure that the Stuff in memory and checksum computed by the CPU arrives exactly like that in the SSD driver. In the past this was a common error source with hardware raid which was faulty. But there is ABSOLUTELY NO checksum for the bits stored on a SSD. So bit rot at the cells of the SSDs are und…

That is ABSOLUTELY incorrect. SSDs have enormous amounts of error detection and correction builtin explicitly because errors on the raw medium are so common that without it you would never be able to read correct data from the device. It has been years since I was familiar enough with the insides of SSDs to tell you exactly what they are doing now, but even ~10-15 years ago it was normal for each raw 2k block to actu…

[deleted]

Re: ZFS: Apple's new filesystem that wasn't (2016)

#79

Earlier quoted context omitted.

Both are imho linked to "offline desktop use cases are not important anymore". Both companies saw their future gains elsewhere, in internet-related functions and what became known as "cloud". No need to have a fancy, featurefull and expensive filesystem when it is only to be used as a cache for remote cloud stuff.

Exactly this. The business case for providing a robust desktop filesystem simply doesn’t exist anymore. 20 years ago, (regular) people stored their data on computers and those needed to be dependable. Phones existed, but not to the extent they do today. Fast forward 20 years, and many people don’t even own a computer (in the traditional sense, many have consoles). People now have their entire life on their phones, ba…

What do you do when you discover that some thing you have not touched in a long time, but suddenly need, is corrupted and all of your backups are corrupt because the corruption happened prior to your 30 day window at OneDrive?

You would have early warning with ZFS. You have data loss with your plan.

Re: ZFS: Apple's new filesystem that wasn't (2016)

#80

I wonder what ZFS in the iPhone would've looked like. As far as I recall, the iPhone didn't have error correcting memory, and ZFS is notorious for corrupting itself when bit flips hit it and break the checksum on disk. ZFS' RAM-hungry nature would've also forced Apple to add more memory to their phone.

ZFS detects corruption. A very long ago someone named cyberjock was a prolific and opinionated proponent of ZFS, who wrote many things about ZFS during a time when the hobbyist community was tiny and not very familiar with how to use it and how it worked. Unfortunately, some of their most misguided and/or outdated thoughts still haunt modern consciousness like an egregore. What you are probably thinking of is the pro…

> Hell, I’ve never even had bad ram.

To what degree can you separate this claim from "I've never noticed RAM failures"?

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