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MacOS may lose data on APFS-formatted disk images

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

#91

Post by freehunter »

torstenvl wrote: post #70
freehunter wrote: post #59

Earlier quoted context omitted.

As well as every version of every OS ever. Windows 98 was the best, Windows XP sucked with it's Fisher Price UI. Then Vista/7 came around and the outcry of "if you want the latest DirectX, you have to upgrade". And then Windows XP was discontinued to much wailing and gnashing of teeth, because XP was the best. Then 8/10 came out and everything was terrible and we're just going to stick to Windows 7 because it's the b…

Cherry-picked anecdotes are worthless. Few if any people glorified Panther when Tiger came out, or Leopard when Snow Leopard came out, or Win3.11 when Win95 came out, or Win95 when Win98 came out, or WinME when WinXP came out, or Vista when Win7 came out. Stop dismissing legitimate complaints just because you worship "new and shiny"

>Stop dismissing legitimate complaints just because you worship "new and shiny"

Yeah, right after you stop dismissing important security updates as "new and shiny".

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

#92

Post by stanmancan »

zbentley wrote: post #85
jandrese wrote: post #80

Earlier quoted context omitted.

My wife's laptop suddenly decided that the boot drive was corrupt a few weeks after she updated to APFS. None of the recovery tools were of any use. We had to reinstall the OS and pull the files from a backup. This story did not make it to Hacker News.

Anecdata != filesystem issue. If you have more information about the problem you encountered and how it implicates/interacts with APFS, please do link to it. Otherwise, bug reports via circumstantial evidence are, while not inherently false, certainly suspect.

I'm not sure they're implying that it -was- an APFS issue, just that in the majority of circumstances users won't go through the same level as effort to diagnose an issue as in the article. Instead of pulling drives and trying to reproduce the error, they just wiped the drive and started fresh.

I could be wrong, but I believe the point is not that it did happen, but that this -could- have happened many times in the past and users just format/re-install without thinking about it.

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

#93

Post by dsharlet »

freehunter wrote: post #55
StillBored wrote: post #46

Earlier quoted context omitted.

How do you know that? Filesystem corruption is frequently silent, and every-time it happens customers don't get on the phone and send the disks to apple so that they can root cause the problem. Its quite possible this bug has happened an untold number of times before it happened to someone who went through the effort to reproduce and isolate it.

>How do you know that? Can you point to any other APFS issues that were reported before this one?

The rest of the post after the question mark you stopped reading at:

> Filesystem corruption is frequently silent, and every-time it happens customers don't get on the phone and send the disks to apple so that they can root cause the problem. Its quite possible this bug has happened an untold number of times before it happened to someone who went through the effort to reproduce and isolate it.

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

#94

Post by testplzignore »

> To prevent errors when a filesystem inside of a sparse image has more free space than the volume holding the sparse image, HFS+ volumes inside sparse images will report an amount of free space slightly less than the amount of free space on the volume on which image resides.

Can anyone explain the "slightly less than" part of this? Why wouldn't it just be "equal to"?

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

#95

Post by praseodym »

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 silently corrupted, even when the actual physical storage layer is perfectly reliable.

A filesystem should be able to last for decades (HFS was designed thirty years ago); I regard not having checksums in a brand new filesystem an over-optimistic tradeoff.

[1] http://dtrace.org/blogs/ahl/2016/06/19/apfs-part5/

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

#96

Post by vvhn »

derefr wrote: post #39

I tend to create sparsebundles to clone my git repos within, to get around the overhead of having huge numbers of inodes on a volume. (Copying, deleting, unpacking archives, Spotlight indexing—all are way slower when you have the worktrees and .git directories from a thousand large repos splayed out across your disk.) So I was a little worried here. Thankfully, I had manually been setting my sparsebundles back to HFS…

Well, APFS is much better suited to this kind of workflow. Create a space shared logical volume inside your container and turn spotlight off on that particular volume (and if you’d like, make that volume case sensitive ). There’s no need to separate that out on a diskimage

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

#97

Post by madeofpalk »

jaaames wrote: post #76
saagarjha wrote: post #37

Sure, it's a new filesystem; it's bound to have bugs. However, one pain point I've identified is that the existing tools often have no idea of how to deal with APFS. I'm currently typing this from a Mac with an APFS drive that is almost certainly experiencing filesystem corruption–I have folders that suddenly lose track of their contents and become impossible to delete ; however, existing tools such as fsck, diskutil…

Yep, I had an APFS volume that I couldn't even health check. I was pretty sure it was filesystem corruption as it'd hang and shut off randomly then come back up without issues, same as when the SSD died the first time. Also am r APFS time machine volume would never finish encrypting, even after being plugged in for days.

Why would you assume that's file system corruption?

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

#98

Post by vvhn »

derefr wrote: post #79
blattimwind wrote: post #51

Earlier quoted context omitted.

TBH an I/O system where having a file system inside a loopback device on another file system is faster than using said file system directly in the first place sounds kinda broken-ish/poorly scaling to me.

Honestly, I don't think there's any way to get around it, if you've got an indexer daemon in the mix. It's pretty much the same as trying to store billions of rows in a RDBMS table, except that file systems+metadata indexes don't have any concept of table partitioning.

Space shared APFS volumes inside a container give you the “table partitioning” you want. You can even set them up to have different case sensitivity options. All your dev work in a case sensitive volume for instance and Adobe software on a case insensitive volume on the same space shared container.

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

#99

Post by praseodym »

huslage wrote: post #50
kbumsik wrote: post #40

Two bugs are described in this article: 1. An APFS volume's free space doesn't reflect a smaller amount of free space on the underlying disk 2. The diskimages-helper application doesn't report errors when write requests fail to grow the disk image These are not even complex problems of the new format. It is just Apple forgot to have basic checks. It is like the root access with an empty password incident happened 2 m…

(1) is incorrect. Sparsebundles are capable of over-provisioning the storage below them _by design_. They always have been. They are, I believe, APFS snapshots essentially now. This behavior is consistent with most other filesystems with similar constructs. (2) is the real issue here.

Sparse bundle disk images [1] are a more efficient way to store disk images on an underlying file system. They are a completely separate concept from the file system in the disk image itself (besides HFS+ apparently doing some intelligent free space reporting) and are definitely not implemented as APFS snapshots.

[1] https://en.wikipedia.org/wiki/Sparse_image#Sparse_bundle_dis...

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

#100

Post by hanklazard »

ReverseCold wrote: post #83
orblivion wrote: post #77

Earlier quoted context omitted.

It's rather obnoxious that they prod us to upgrade every other day while all this is in the news.

I updated day one and had usual apple problems (finder broke so I had to use my terminal, sometimes it wouldn't wake up from sleep so I had to force it to reboot, my fans would spin up for seemingly no reason). Most of the issues were fixed a week later or so. Anyway, I recently switched to Arch on a 2018 LG Gram and I'm not really missing anything. Battery life is great (8-12 hours of Firefox) and it has a quad core…

Yeah, same. I couldn't stomach the port situation on the new macbooks (and the High Sierra issues) so ended up with a 4th gen Lenovo Carbon X1. Wiped Windows 10 and installed Mint. The whole process was dead-simple and I couldn't be happier with it.
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