Live data from Hacker News

MacOS may lose data on APFS-formatted disk images

bombich.com

161–170 of 193 posts

Re: MacOS may lose data on APFS-formatted disk images

#161
I get the feeling that many of those who comment didn’t read the article. It says

> Note: What I describe below applies to APFS sparse disk images only — ordinary APFS volumes (e.g. your SSD startup disk) are not affected by this problem. While the underlying problem here is very serious, this is not likely to be a widespread problem, and will be most applicable to a small subset of backups.

Re: MacOS may lose data on APFS-formatted disk images

#162
post #105

APFS not having block or file-level checksums really seems like a big oversight to me. While the filesystem’s designers considered the hardware-level guarantees to be sufficient [1], this issue shows that there is an entire class of problems that they have not considered. Disk images and loopback-mounted filesystems or even disk-level cloning introduce additional layers of complexity where a filesystem can be silentl…

Apple HFS+ didn't have file data checksums either. The default filesystem on most Linux distributions, ext4 doesn't, it just stores checksums of the file metadata, not the file data. Same story with Windows NTFS filesystem. Microsofts newer ReFS filesystem has file data checksums disabled by default. So it seems like a tradeoff that most of the major operating system are making. Most likely related to performance. Ed…

Performance is only an issue if your disk can write faster than your CPU can hash. hammer2 changed its hash a couple of years ago because this started happening with newer NVMe drives[0], but before that disk writes weren't CPU-bound.

[0] http://lists.dragonflybsd.org/pipermail/commits/2016-June/50...

Re: MacOS may lose data on APFS-formatted disk images

#163
post #131

Earlier quoted context omitted.

I had to make room on my MBP SSD to install windows through bootcamp and bashed my head against a wall on the same issue. It took me half an hour to find the reason why so much of my hard drive wasn't available despite me having deleted almost all third party apps and personal data on my macOS partition. Time Machine does 'local backups' and there is NOWHERE in the user interface that fully explains the space they oc…

Yes it’s a really poor design decision. They could have at least added “local time machine backups” color to Disk Utility, or added a way to turn them off. Agreed re: snappiness of other OS. Ubuntu flies on my 2013 MBP.

There used to be a way to turn in off before High Sierra, now the only thing you can do is delete the local snapshots. [0]

[0] https://forums.macrumors.com/threads/solution-reclaim-storag...

Re: MacOS may lose data on APFS-formatted disk images

#164

Yet another reason to stick with El Capitan.

I really want to- but I'm locked out of Xcode 9 if I linger. If only I can run it through some sort of virtualization

VMware Fusion supports High Sierra as guest including APFS. I was under the impression that Parallels does the same. Not sure about Virtual Box though.

Re: MacOS may lose data on APFS-formatted disk images

#165
post #116

Yes, fairly limited impact, but still. Data loss is fucking important. We aren't talking about an occasional stutter when moving windows or a sound driver that sometimes needs a reboot to resume working. This is a major bug. I would really really like it if Apple would get their shit together so that people who actually rely on their computers to work correctly can upgrade at some point.

Or just stop using macOS. I wish I could give you my Debian Thinkpad for a week. Granted I've put some time into tweaking it because the sock gnome3 rounded matte shit is shit, but I bet you'd convert. The only issue is the screen aspect ratio Apple still wins there.

I could never go without Notational Velocity. It's worth more than the whole OS.

Re: MacOS may lose data on APFS-formatted disk images

#166
post #115

Earlier quoted context omitted.

refs (microsoft's new filesystem)'s deployment went along much better. i haven't heard of any major issues since it came out in windows server 2012.

ReFS was only ever made the default on new installs of Windows Server 2012. It never actually made it to production builds of Windows 8 or above so it's actually only installed on a fraction of the systems that are out there. That's not really a sufficient sampling size to say that this deployment went along much better. The APFS update was a much, much larger endeavor and, based only on public response, was nearly s…

yes, huge deploy but not that seamless.

1. i had a filevault related corruption issue, the disk was eating itself up thinking it was encrypting... don't have the apple discussion link at hand.

2. time machine hidden snapshot, "disk full" issues. it's a major pita for me that is not possible to turn off local snapshots.

Re: MacOS may lose data on APFS-formatted disk images

#167
post #105

Earlier quoted context omitted.

Apple HFS+ didn't have file data checksums either. The default filesystem on most Linux distributions, ext4 doesn't, it just stores checksums of the file metadata, not the file data. Same story with Windows NTFS filesystem. Microsofts newer ReFS filesystem has file data checksums disabled by default. So it seems like a tradeoff that most of the major operating system are making. Most likely related to performance. Ed…

Performance is only an issue if your disk can write faster than your CPU can hash. hammer2 changed its hash a couple of years ago because this started happening with newer NVMe drives[0], but before that disk writes weren't CPU-bound. [0] http://lists.dragonflybsd.org/pipermail/commits/2016-June/50...

What about: * Disk reads may unnecessarily trash the CPU caches, because CPU will need to verify the checksum when the DMA read is done, even if the app isn't going to process the data immediately afterwards * Battery life - without checksums the CPU can stay mostly idle, and go into a lower power mode, while the disk controller does its job

Re: MacOS may lose data on APFS-formatted disk images

#168

Earlier quoted context omitted.

200B in the bank and they couldn’t find a way to port it to other platforms? I think they could.

It’s not about not being able to port it; it’s not the right tool for the job. ZFS is a file system designed for servers; the Apple Watch, Apple TV and the iPhone and iPad aren’t servers.

That doesn't mean it can't be adapted and tuned for mobile. The average smartwatch has more processing power than the average server did at the time the ZFS project was launched (2001).

Re: MacOS may lose data on APFS-formatted disk images

#169

A friend of mine lost a ton of data this week after mac os crashed and he restarted it. The only things he had done since getting the computer a week ago were: 1. update to high sierra 2. copy over files from old mac 3. record about 40gb of screen share data using quicktime (which is what he was doing when it crashed) He spent hours on the phone with apple, the tech said he had never seen anything like it and they we…

I had a kernel panic a few weeks ago that left the OS in a state where it was unable to boot. It seemed to think it was mid-upgrade and was complaining about missing the packages an upgrade would read from. Thankfully macOS has an in-place OS reinstall option and as far as I’ve been able to see all my data is totally fine. But it was bizarre and I’ve never experienced anything like it in a decade of using Macs.

Re: MacOS may lose data on APFS-formatted disk images

#170
post #21

Earlier quoted context omitted.

Honestly, it's the first Mac OS release I'd actively recommend avoiding upgrading to. It offers essentially no benefits over the prior release, and a whole lot of downsides. (Security issues notwithstanding, High Sierra also drops compatibility for a lot of older software.)

Lion actively screwed up normal people's workflows with the botched "Save As" replacement. I still want an explanation of why they thought that was a good idea. We skipped that one after one of the admin assistants discovered the new joy. The whole California-series of OS has had a broken Finder. I see some fixes in High Sierra, but its still buggy as heck for large file moves and broken scripting. I'm hoping they ta…

I would be very happy to see macOS drop back to bi-yearly/loose schedule upgrades. It’s a mature platform that runs on hardware that improves significantly slower than the hardware iOS runs on; at this point insisting on a new release every year rather than when it’s ready is actively detrimental. As much as I still get excited by new features and tech, I use my Mac exclusively for work, and rock solid reliability is more important to me than new features.
Post reply on HN