My Mac Crashed Again

by Ron Gilbert
Jul 09, 2016

My Mac crashed again and won't fully boot, saying the drive is corrupt.  I now suspect it's Photoshop that is causing this.  The last time this happened, the night before I was working on a huge file and Photoshop started to tell me the file was too big, and then it was reporting it was unable to save the file.  The next day, my machine wouldn't fully boot due to the keychain being corrupt.

This morning, I was working on a large Photoshop file and I started to get the same errors, when I rebooted, my keychain was corrupt.

I'm going to head into the Apple store and see if they can fix it without a reformat this time.

Why am I telling you this?  Because I was going to put up the new podcast and that might not happen.


Back from the Apple store with a freshly reformatted machine and time machine pulled everything back.

I mentioned to the Genius Bar tech person that this is the second time it's hard crashed from editing a large file in Photoshop and he said "oh...", then we had a conversation that I can only assume was "off the record" by the way he spoke, tell me other people have reported drive corruption when extremely large files are process by fusion drives.

Yeah... no kidding.

I'll do a little Googling and see if I can find anything. Like I said in my previous post, I don't trust fusion drives and I guess with good reason.

I do need to re-edit the podcast, so that will go up tomorrow.

- Ron

Big Red Button - Jul 09, 2016 at 13:16
That's interesting, seeing that Macs are very popular among Photoshop users just because of the dependability.

PS: Do you mean that it might not happen at all, or not happen yet?

Ron Gilbert - Jul 09, 2016 at 13:18
I have the raw files for the podcast, but lost the edited ones, so I'll have to reedit if I can't get them back.  Last time, I was able to access the dive before being reformatted, so all might not be lost.

Thomas Knox - Jul 09, 2016 at 14:11
If I had to make an educated guess, I'd say that you have 1 or more RAM sticks that are on the iffy side of life and when you start hitting them with repeated access, they choke. Hopefully you bought the RAM from Apple. :)

It *could* be that your hard drive is faulty and when your Mac is writing out the page file for VM swappiness, it corrupts the data, but that's unlikely if you're not getting corruption in other documents and random crashes all the time. I'm putting my money on bad RAM.

Ron Gilbert - Jul 09, 2016 at 14:34
I've thought of that, but do to the machine being used for dev, I'm often using a lot of memory, so it's hard to believe that is the issue. I could be wrong.

Run - Jul 09, 2016 at 15:10
You could try to run Memtest86(+)

DZ-Jay - Jul 12, 2016 at 05:39
Dear Mr. Gilbert,

I've used TechTool Pro successfully to diagnose memory and HDD issues.  I believe that the latest version supports Fusion Drives.

If I had to guess, I would say the problem is an edge-case within the immature technology of Fusion Drives (or their drivers).  Since they try to keep in-memory cached images synchronised with the physical disk, there may be some conditions that cause them to go out of sync.

Whenever I get the itch to try one, I remind myself that it took 10 or 15 years for consumer-grade HDD and file-systems that support them to become reliable enough.  Remember the time when sneezing close to the machine could corrupt your Master Boot Record?


Gffp - Jul 09, 2016 at 14:28
Ron, can I ask you if this crash is related to the fusion drive? In other words, do you think it's safer to work on a Mac that doesn't have a fusion drive?

Ron Gilbert - Jul 09, 2016 at 14:32
Hard to say. It could have something to do with the large file being spooled to the HD. It's hard to tell.

Brian Small - Jul 09, 2016 at 15:36
I hope you don't lose your files.

When did you buy your iMac?  Could this issue be related to yours?

Gffp - Jul 09, 2016 at 21:38
Ron, when months ago I read the post of the first crash, I asked my two friends who use iMac. None of them ever had issues working on large photoshop files (a professional photographer and an architect and visual artist). None of them have fusion drives. I made some googling, and I found some articles written by end-users about issues on fusion drives like yours.

Lukas - Jul 10, 2016 at 02:32
The simple answer is: yes, it's always safer to use non-hybrid disks. Personally, I think hybrid disks are a bad idea.

Basically, even if everything works absolutely perfectly, having two disks that rely on each other doubles your chances of disk failure. If one of them goes, your data goes.

Modern drives store a lot of bits on a tiny amount of space. In order to achieve this, they use a lot of questionably techniques. For example, instead of having two charges ("no charge" or "full charge") for one and zero, an SSD might charge the capacitors only partially to achieve four or more different states, store two or more bytes in one capacitor, and then fix the errors caused by them using statistical analysis ("this was most likely intended to be 01 when it was stored, but could also have been 00, and we'll pick the correct choice based on the parity bit).

So you already start out with disks that are very likely to eventually develop problems, and be unable to retrieve all of your data properly.

And then you add a second disk to this fragile system - if either disk fails, your whole system fails.

So these systems are a bad idea. I'm using a hybrid disk in my PS4, because it doesn't matter too much if the disk goes belly-up, but when my PC came preinstalled with a hybrid disk, I immediately took it out and put in a real SSD.

Bogdan Barbu - Jul 10, 2016 at 10:01
SSD's. Typically use NAND flash, not capacitors. Capacitors can't really be used for non-volatile storage; you're probably thinking of DRAM.

Lukas - Jul 10, 2016 at 14:15

Iron Curtain - Jul 11, 2016 at 10:54
I blame Tim Cook for this. I don't think Steve Jobs would ever let Apple have something so repetitively buggy therein without extensive testing. Or at least not to Tim Cook's extent.

Bogdan Barbu - Jul 09, 2016 at 21:02
I can't speak for everyone here but as far as I'm concerned, re-eding the podcast is probably not worth it. You'd be wasting precious development time and we'd be getting out-of-date information about the state of the game. We've missed podcasts before, we could just wait for the next one.

Mattias Cedervall - Jul 10, 2016 at 19:32
I disagree! The podcasts are a part of the documentation of the making of Thimbleweed Park and it will be game designer-history in the future for other game designers to learn from.

Krzysiek - Jul 09, 2016 at 14:28
Get DiscWarrior. The only app (in my experience) that can recover data from a drive that is corrupt (which the system app cannot fix).

Ron Gilbert - Jul 09, 2016 at 14:31
I have DiskWarror, but it won't boot as an external drive. I don't know if the stick is bad, or the Mac is bad. I bough it after my last crash and am disappointed that it doesn't work.

Thomas Knox - Jul 10, 2016 at 01:18
There's an app on the DW USB stick that will let you create your own bootable USB drive with DW on it. I had to make one because the CD/USB drive that came with v4/v5 wouldn't boot my iMac. It would just hang. Making the bootable USB drive myself worked like a charm.

Mattias Cedervall - Jul 09, 2016 at 16:06
I'm sorry to hear that! :-( I hope you'll find a solution, Ron.

sex - Jul 09, 2016 at 17:41
You could let the MacStore do a full sys check. Physically differ between os/progs/... and data (like, a robust drive/server which mirrors according to your needs). Otherwise it's mostly a matter of time, and how badly you want data back, until you need a recovery service. @Photoshop: You might want to stick to a version (on a project basis) you can trust or look if there exist options which suit your needs.

Completely unrelated but on a scale from "Huh?" to "Until hell..." how likely could it be, getting chip sound as an option on top?

Mario F. - Jul 09, 2016 at 19:33
Do we need to delay the game? oh yeah, then put up the imac problem again for a while. hahaha

Jens - Jul 09, 2016 at 19:33
Hi Ron,
have you tried using Affinity Photo ( instead of Photoshop?
I have switched last year, when it came out and never looked back at the subscription model ...

Paulup - Jul 09, 2016 at 19:46
No more excuses, if that podcast isn't on my desk first thing tomorrow morning then you're in detention for two weeks.
And Gary and David, I don't know what you find so funny, if you don't get back to work you'll both be joining Ron in detention, etc., etc.

Orcan Ogetbil - Jul 09, 2016 at 22:54
Maybe it is a sign. Or the curse of the evil meteor.

Man who jumps on dirt - Jul 10, 2016 at 02:43
I didnt get a mailtron3000 message for this..... is that out of order, or do I need to subscribe again, or what?

Big Red Button - Jul 10, 2016 at 05:59
Don't worry. There was no mail this time.

Ipnotik - Jul 10, 2016 at 05:47
i have a fusion drive too on my imac 5k and I extensively use ps for my job. Never had any of your probelms so I think that somethng wrong is occurred in your machine and probably ssd drive and/or hd drive are physically damaged . However for the next time (hope not of course) I can tell you a very simple procedure to get rid of your travels to the apple store but I repeat probably there is something wrong with your machine. You should try to install everything to an external thunderbolt ssd drive and see what happens...ciao and good luck!

Andrew Herron - Jul 10, 2016 at 10:16
When formatting it one of those funky shell commands can split the fusion drive giving you a small pure SSD (I suggest boot from that) and the big drive for storage.

Way less convenient, but if it happens a third time it might stop the fourth...

Stefan - Jul 10, 2016 at 12:14
Use a Windows PC and everything is fine ;-)

Big Red Button - Jul 10, 2016 at 12:41
In terms of PS, I don't think so.

Though, I've always thought that a typical programmer would work on Linux. Maybe this has changed over the years in favor of Apple.

Big Red Button - Jul 10, 2016 at 13:07
Of course, I meant "use Linux", not "work on".

Mario F. - Jul 10, 2016 at 16:47
I work with psd on PC with large files. 5GB Psd files. Ssd drive and 64 GB RAM. Easy and never crashed so far.

Gzurl - Jul 10, 2016 at 13:49
What is clear to me is that Apple should compensate this by becoming one of the big backers of Thimbleweed Park :-)

Gffp - Jul 10, 2016 at 14:43
+ 1

Gffp - Jul 10, 2016 at 14:44
Here's one of the articles I found about fusion drive back then:

Ron Gilbert - Jul 10, 2016 at 17:30
When I say large files, I mean LARGE files. I was working on a large file and went to change the size and entered 8000 for pixels, but it was set to percent, so it tried to enlarge the file by 8000% (and had over 100 layers). It churned for a while and then I got an error saying the file was too large for PS, then a minute later, I started to get the corruption errors. So when I say "large" files, I'm not talking about normal large files.

Gffp - Jul 10, 2016 at 18:37
Hmmm... I don't know about the photographer, for sure  I saw the architect work on a ps file (a page layout for a project presentation) with something like sixty layers, many images imported from cad (vector graphics) and very high resolution photos (made with a reflex of something like 40 megapixel)... But I'm sorry I don't know if this can be considered a LARGE (probably not) or a simply large file eheheh... If I understood it was an error that caused the crash, trying to enlarge the image to 8000 percent instead of 8000 pixel. A mistake could happen, and I remember some crashes of PS, but why this has to involve the entire OS? It's strange.

Simon Simon - Jul 11, 2016 at 03:35
Because for extremely large files, PS typically tends to create even huger scratch files on disk.  - this behaviour will pretty much reveal if on one's system (= your fusion drive  / file system / etc. ) has unreliable large file handling.

Christian Stigen Larsen - Jul 11, 2016 at 09:00
I would be surprised if one app (Photoshop) could wreck the HD and not another, unless it's accessing the drive in unconventional ways. You could in theory just write a short program that fills up the HD, and then see what happens (or, if that doesn't work, fill up as much memory as you can, to see if the trip through the VM is causing problems).

me - Jul 30, 2016 at 12:16

A simple script can test and discover the root of the problem (and crash your computer again)

But it is worth it. For science!

Santiago - Jul 10, 2016 at 21:08
That computer behind the girl is a Commodore 64??❤️

Mister T - Jul 11, 2016 at 07:12
Looks like there are the function keys. And the big external floppy disc drive.

longuist - Jul 11, 2016 at 06:41
Even if its not 100% proven the fusion drive is the culprit its worth a try. You could buy a 2TB SSD (about 650$) from kickstarter money. The day (probably less) lost for transferring the system would be better than a crash to the worst possible time.

Óscar - Jul 11, 2016 at 07:13
Fix procedure:

1. Format
2. Install Linux
3. Enjoy :D

Tom - Jul 11, 2016 at 08:40
Having a NAS with real time backup enabled is a good idea.

Big Red Button - Jul 11, 2016 at 09:41
What about using an SSD for the OS + all programs, and a conventional HDD for working data?

Necrosis Thanatos - Jul 11, 2016 at 15:53
The actual problem is that it's a Mac.  Either that or the guy behind the keyboard.  :-)

Big Red Button - Jul 12, 2016 at 09:17
How polite! :)

Arttu - Jul 13, 2016 at 02:48
Comment on the fusion drive. In our company, some developers had new Windows workstations with hybrid drives. We had both laptops and desktops. Soon a few of them started to experience file corruption or intermittent freezes. These continued until we replaced hybrid drives with SSDs. My experience was that about half of the disks had problems and that's too much, even for Seagate. I would recommend replacing the drive, especially as you have had this problem before.

Marko - Jul 18, 2016 at 08:05
Hi Ron,

I work professionally with Mac systems and can highly recommend you split the Fusion drive. I would use the SSD bit for the operating system and Apps, the spinning hard disk should be used to store all your data. I always mount the spinning disk to /User.

Get in touch if you want some help configuring this.


Sir Swing - Jul 18, 2016 at 10:10
Is that a goatee on the girl?

Nor Treblig - Jul 18, 2016 at 20:18
Oh my, what have you done! :D