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Apple Silicon Macs can't boot from external drive if internal drive failed

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Re: Apple Silicon Macs can't boot from external drive if internal drive failed

#171

Post by toast0 »

Dylan16807 wrote: post #115
ChuckNorris89 wrote: post #76

Earlier quoted context omitted.

>whatever failure damaged the SSD is statistically likely to compromise the reliability of the rest of the board Sorry, but how? That's just reads like BS. SSDs have limited lifespans due to the limited write cycles of the NAND chips. So no, what damages NAND does not damage the rest of the board. The more you write and swap to flash, the faster it wears out, taking your Macbook down with it when it dies. Granted, I…

How many SSDs have you worn out? I've never managed it.

I've had hundreds of enterprise SSDs fail on my servers, but only a couple had any pre-failure indicators in SMART, including write volume which was pretty low. The post-failure indicator was almost consistently no longer visible through the disk controller.

Failure rate was much less than enterprise spinning disks, but at least with the spinners failed, you could still see them and get most of the data off, if you needed to. And they had reliable pre-failure indications.

TLDR: take regular backups and plan for storage to fail (which for soldered storage means plan to get a new device, I guess)

Re: Apple Silicon Macs can't boot from external drive if internal drive failed

#172

Post by londons_explore »

wtallis wrote: post #110
ChuckNorris89 wrote: post #76

Earlier quoted context omitted.

>whatever failure damaged the SSD is statistically likely to compromise the reliability of the rest of the board Sorry, but how? That's just reads like BS. SSDs have limited lifespans due to the limited write cycles of the NAND chips. So no, what damages NAND does not damage the rest of the board. The more you write and swap to flash, the faster it wears out, taking your Macbook down with it when it dies. Granted, I…

In practice, exhausting NAND write endurance is usually not what causes SSDs to fail in the field. It is especially unlikely to be the underlying cause of unexpected and seemingly premature catastrophic SSD failure. Also, it is not possible for an SSD to decrease your usable storage space over time. That would break any partition table format or filesystem that expects an ordinary block device. It also wouldn't win y…

> Also, it is not possible for an SSD to decrease your usable storage space over time.

It totally could be possible. For Windows/Linux, you could have a daemon that creates a 'ssd_wear' file which grows in size as the SSD wears out, and messages to the SSD which physical blocks it occupies. Mac could obviously do a deeper integration directly into the OS.

> all of your blocks are on the verge of failure

A failed block still stores some information (in an information entropy sense). It's totally possible to store one blocks worth of information across two, four, or eight failed blocks (with extra error correction information).

Combining these two techniques, an SSD should never fail. Instead it slows down and gets smaller. Sadly as far as I'm aware, no consumer drive vendor has implemented these.

Re: Apple Silicon Macs can't boot from external drive if internal drive failed

#173

Post by xxpor »

niklasrde wrote: post #10

Does that apply to PXE or the Mac equivalent? I wonder how they will run their diagnistics in the Apple Store if they can't boot their diagnostics tool.

If they're loading the EFI image off of the SSD, it'd affect that too (unless there's PXE in the bootstrap code, but I seriously doubt it)

Re: Apple Silicon Macs can't boot from external drive if internal drive failed

#174

Post by marmaduke »

GhettoComputers wrote: post #17
gameswithgo wrote: post #7

Consider options like Framework laptops that let you actually own your hardware, and repair it.

Silly idea in tech, the hardware will be long outdated before someone look for parts which are going to be overpriced, and the company might be gone forever. You can buy common business laptops such as thinkpad and swap the parts easily and cheaply. People aren’t swapping their 2011 i3 for a 2011 i7 if they care about performance; they’re getting an i5 from 2018. None of these swappable parts are unique aside from th…

We have a compute cluster made mainly of Westmere-generation Xeons from 2011, which has been the workhorse for research publications from our group for a decade. They are still running fine, the (non soldered, replaceable) ECC DRAM chips are failing before anything else.

Re: Apple Silicon Macs can't boot from external drive if internal drive failed

#175

Post by lotsofpulp »

fsflover wrote: post #169
lotsofpulp wrote: post #127

Earlier quoted context omitted.

Apple is targeting the population that has no need for upgrades. Watching videos, browsing internet, sharing pictures and videos, video calling and basic spreadsheet/word processing needs no upgrades. I use a 2015 MacBook Air and I don’t need an upgrade, and I probably do more on my laptop than 80% of people.

> Apple is targeting the population that has no need for upgrades. And also those who very frequently do backups, because restoring the data from a failed SSD would be problematic.

Yes, Apple is also probably not targeting the population of people who cannot backup to iCloud and also not backup regularly to a NAS or USB via Time Machine.

Re: Apple Silicon Macs can't boot from external drive if internal drive failed

#176

Post by jackorange »

slownews45 wrote: post #156
aneutron wrote: post #118

I get that the memory bandwidth and performance of the SoC is intimately tied to the CPU, GPU and memory being on the same silicon (grossly vulgarizing the approach). However, there is no reasonable justification (as far as I can tell) for why the SSD would have to be soldered onto the same SoC, and even less reasonable justification for why the iBoot stuff couldn't be located on an EEPROM or something of the sort, l…

Does anyone laugh a bit at these types of comments? Using these "stupid" and "unjustifiable" approaches, apple has delivered highly reliable / fast machines to lots of users. They come with applecare if you want, which gets you walk in fix/replace at their stores. Note, they've already don't this on iphones - millions shipped. They are going for as much reliability / speed out of this for the 90%+ of users who are no…

Maybe others will also take after apple selling $99 stands and $7 small microfiber cloths.

Re: Apple Silicon Macs can't boot from external drive if internal drive failed

#177

Post by codetrotter »

lamontcg wrote: post #139
liminalsunset wrote: post #26

General grumpiness about this particular design decision aside, it appears that since the T2 Macs, the main SSD was being used to store core system firmware. On T2 I think it's BridgeOS that sends the EFI image to the Intel side to boot it, and it does the firmware verification and loading. This setup has a benefit; namely, it is now impossible to brick the system with a bad BIOS/EFI flash, and you'll never need to u…

> The SSD is reasonably considered to last the "lifetime" of the product Except for simply running of out drive space. So if you want to buy something and have it last 5+ years you need to spec it out from the start to have way more drive space than you think you'll ever use. Or else when it runs out and you really need that extra space you're forced to upgrade everything in order to get the extra space since you mad…

> Except for simply running of out drive space.

> So if you want to buy something and have it last 5+ years you need to spec it out from the start to have way more drive space than you think you'll ever use.

Yup. When I bought my MBP M1 2020, I foolishly went with 256GB of storage.

Installed Xcode and that was like 15GB of available storage space gone right then and there. The simulators take another few GB on top of that.

Add to that all of the other software that I use, another significant portion of storage space is taken.

And with my own files on top, I routinely have only about 10-15 GB of available space out of the 256 GB, which is quite annoying. And it also means not being able to install some stuff that I use only sometimes, because with the limited amount of space I have I cannot waste it on things that I only rarely use. But that means I don’t get to use those things at all unfortunately.

Not being able to do anything about this is about the only gripe I have with this machine. So all in all I am still very happy with it. But not as happy as I would’ve been if I wasn’t constantly running out of storage space.

And I even thought I was giving myself enough room for everything, because my previous computer was a MacBook Air 2018 model with 128GB storage, where I was also running out of space all the time, so even though I really wanted to buy the 1TB model of MBP M1 2020 I landed on the 256GB thinking that hey it’s still twice what I had so it should be enough right. Well, no, not quite enough as it soon turned out.

Re: Apple Silicon Macs can't boot from external drive if internal drive failed

#178

Post by 1123581321 »

KennyBlanken wrote: post #170
1123581321 wrote: post #96

Earlier quoted context omitted.

I think you are using old information. Any modern SSD should be good for a few hundred to several hundred TB and may reach a PB. It would be very hard to use a personal computer that heavily. Most people would take 20 years or more.

That's not how SSD wear works because nobody completely writes to their SSD, erases it, and writes again. You can't wear-level against blocks that are in use, only blocks that are free. If every person I've helped socially and professionally is any indication, people keep their storage anywhere between 80% and 95% full. At 95% full, all your write cycles are focused on just 5% (plus spare provisioned blocks.) Think a…

I did not say SSD wear works that way. All of that is factored into the usage I cited—-swap, system writes, etc. do not wear the drive as much as you appear to think for most users.

Re: Apple Silicon Macs can't boot from external drive if internal drive failed

#179

Post by 1123581321 »

sofixa wrote: post #144
1123581321 wrote: post #96

Earlier quoted context omitted.

I think you are using old information. Any modern SSD should be good for a few hundred to several hundred TB and may reach a PB. It would be very hard to use a personal computer that heavily. Most people would take 20 years or more.

You're forgetting swap. Not to mention professionals in domains like photography, design, video, etc. who might chew through big files frequently.

Swap and other system activity is factored. Most heavy workloads wear other parts of the system as well. As another user pointed out, truly heavy storage and scratch system based workloads want to use large externals anyway, for other reasons.

Re: Apple Silicon Macs can't boot from external drive if internal drive failed

#180

Post by wtallis »

londons_explore wrote: post #172
wtallis wrote: post #110

Earlier quoted context omitted.

In practice, exhausting NAND write endurance is usually not what causes SSDs to fail in the field. It is especially unlikely to be the underlying cause of unexpected and seemingly premature catastrophic SSD failure. Also, it is not possible for an SSD to decrease your usable storage space over time. That would break any partition table format or filesystem that expects an ordinary block device. It also wouldn't win y…

> Also, it is not possible for an SSD to decrease your usable storage space over time. It totally could be possible. For Windows/Linux, you could have a daemon that creates a 'ssd_wear' file which grows in size as the SSD wears out, and messages to the SSD which physical blocks it occupies. Mac could obviously do a deeper integration directly into the OS. > all of your blocks are on the verge of failure A failed bloc…

You should read up on Zoned Storage for NVMe SSDs, and some of the more recently added error handling features like Get LBA Status. The gist is that it is only practical for the SSD to be in charge of determining what has failed-not the host, and that retrofitting NAND retirement into the traditional block device/LBA model is not worth the trouble when there are also other reasons to migrate to a different, more flash-friendly abstraction.
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