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Groups > comp.sys.mac.system > #119585
| From | Lewis <g.kreme@gmail.com.dontsendmecopies> |
|---|---|
| Newsgroups | comp.sys.mac.system |
| Subject | Re: APFS on HDD |
| Date | 2018-11-19 05:46 +0000 |
| Organization | Miskatonic U |
| Message-ID | <slrnpv4ji7.2rih.g.kreme@Snow.local> (permalink) |
| References | (18 earlier) <RWJHD.307536$rK2.124531@fx28.iad> <1nyf1cp.1xsp53r4hod6uN%dempson@actrix.gen.nz> <BTlID.572643$sO2.508519@fx41.iad> <slrnpv46p1.2did.g.kreme@Snow.local> <1nyiqcn.1rpsrwgn7nqxdN%dempson@actrix.gen.nz> |
In message <1nyiqcn.1rpsrwgn7nqxdN%dempson@actrix.gen.nz> David Empson <dempson@actrix.gen.nz> wrote:
> Lewis <g.kreme@gmail.com.dontsendmecopies> wrote:
>> In message <BTlID.572643$sO2.508519@fx41.iad> JF Mezei <jfmezei.spamnot@
>> vaxination.ca> wrote:
>> > On 2018-11-18 00:37, David Empson wrote:
>>
>> >> That may have been the case in APFS version 1 (developer preview on
>> >> Sierra), which Apple hasn't documented in detail. I haven't tried
>> >> multi-volume boot scenerios yet, except in separate
>> >> partitions/containers.
>>
>> > When I watched the APFS presentation in 2017, it mentiond that APFS
>> > basically placed the boot information (block location, number of blocks
>> > to load etc) in block 0 of the GPT partition where the EFI firmware
>> > would look to see if the GPT partition was bootable.
>>
>> > So from an EFI point of view, it could only see one bootable volume in
>> > the GPT partition that containes the APFS container which may contain
>> > multiple bootable APFS volumes)
>>
>> I do not elive these two paragraphs are accurate or display am
>> understanding of how file systems work or anything abotu APFS.
> Both paragraphs have details wrong but the basic concept is correct.
>> We know for absolute fact that a disk in a mac can have multiple boot
>> volumes. This has been true as long as the Mac has supported hard
>> drives. Possibly longer.
> That's true for drives with mulitple partitions with older file systems
> where each partition holds a single volume, but each APFS partition is a
> container which can hold multiple volumes.
And yet we know that a single APFS continer can hold multiple bootable partitions.
> The EFI firmware understands nothing about APFS beyond identifying an
> APFS partition/container, and loading an EFI jumpstart driver (which is
> an EFI program) from the APFS container. The EFI jumpstart driver is
> pointed to by the container's superblock, which has a copy in block 0 of
> the partition.
> The EFI firmware is unaware of volumes inside the APFS container.
Right.
> That means if you have a single APFS container with mulitple bootable
> volumes inside it, the EFI Startup Manager (option key at startup)
> cannot offer those volumes to you, because it doesn't kwow they exist.
Wrong.
> It will show a single icon and name for the APFS container.
Nope. My startup drive has six APFS volumes on it
/dev/disk2 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +959.3 GB disk2
Physical Store disk1s2
1: APFS Volume Jaka 625.4 GB disk2s1
2: APFS Volume Preboot 45.4 MB disk2s2
3: APFS Volume Recovery 1.0 GB disk2s3
4: APFS Volume VM 2.1 GB disk2s4
5: APFS Volume Mojave 13.7 GB disk2s5
6: APFS Volume High 11.9 GB disk2s7
If I hold down the option key at boot I am offered a choice between
Jaka (Current Mojave with all the user data), Mojave (has 10.14.0 with
no user data), and High (10.13.$LATEST) with no user data.
> Which APFS volume that boots is determined by the EFI jumpstart driver
> read from the container, and the information it reads from the Preboot
> volume. (It may divert to the recovery volume, e.g. by holding down the
> right keys at startup.) The preboot volume information is typically set
> by Startup Disk in System Preferences.
It does appear that preboot is the mechanism that Apple uses to decide
which volume boots, but it also appears it has the information that EFI
needs to list all the bootable volumes (except recovery, but that was a
deliberate choice by Apple).
> Since EFI programs can present a user interface, if Apple wanted they
> could have the EFI jumpstart driver present an interface resembling the
> Startup Manager which let you pick between multiple bootable volumes
> inside the container. They probably don't think it is worth confusing
> the user by adding a second layer of bootable volume selection at
> startup for something which very few users would bother setting up, and
> those who do can use Startup Disk in System Preferences to change the
> boot volume.
There is no second layer at all, it simply lists each bootable volume.
> You _can_ have a drive which has multiple APFS partitions (containers)
> each with a single bootable volume, and pick between those containers in
> the Startup Manager. This prevents free space sharing between the APFS
> volumes because they are in different APFS containers.
Which is why I didn't do it. And I'm not sure it works since I've never
tried it. However, multiple bootable volumes in one container absolutely
does work.
> Multiple bootable volumes in separate partitions, yes.
> You can't have multiple bootable volumes inside a single APFS container
> (partition) and expect to be able to pick among them at startup of the
> computer (while EFI is the only software running).
You absolutely can, and I've had this setup since the Mojave beta.
--
And east is east and west is west and if you take cranberries and stew
them like applesauce they taste much more like prunes than rhubarb does.
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Re: APFS on HDD rs99tl@gmail.com - 2018-11-09 17:32 -0800
Re: APFS on HDD Your Name <YourName@YourISP.com> - 2018-11-10 14:42 +1300
Re: APFS on HDD RSORLANDO <rs99tl@gmail.com> - 2018-11-09 18:15 -0800
Re: APFS on HDD Elden <usenet@moondog.org> - 2018-11-09 21:27 -0800
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-10 18:52 +1300
Re: APFS on HDD J Burns <burns@nospam.com> - 2018-11-10 09:11 -0500
Re: APFS on HDD Your Name <YourName@YourISP.com> - 2018-11-11 10:08 +1300
Re: APFS on HDD J Burns <burns@nospam.com> - 2018-11-10 17:41 -0500
Re: APFS on HDD nospam <nospam@nospam.invalid> - 2018-11-10 19:18 -0500
Re: APFS on HDD Your Name <YourName@YourISP.com> - 2018-11-11 18:03 +1300
Re: APFS on HDD J Burns <burns@nospam.com> - 2018-11-11 13:21 -0500
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-12 03:09 +0000
Re: APFS on HDD J Burns <burns@nospam.com> - 2018-11-12 02:10 -0500
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-12 12:32 +0000
Re: APFS on HDD Your Name <YourName@YourISP.com> - 2018-11-13 08:14 +1300
Re: APFS on HDD J Burns <burns@nospam.com> - 2018-11-12 20:29 -0500
Re: APFS on HDD Your Name <YourName@YourISP.com> - 2018-11-13 18:15 +1300
Re: APFS on HDD J Burns <burns@nospam.com> - 2018-11-13 09:20 -0500
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-12 02:30 -0500
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-12 12:45 +0000
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-12 18:31 -0500
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-13 00:04 +0000
Re: APFS on HDD Your Name <YourName@YourISP.com> - 2018-11-13 13:46 +1300
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-11 15:55 +1300
Re: APFS on HDD J Burns <burns@nospam.com> - 2018-11-10 23:38 -0500
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-11 07:18 +0000
Re: APFS on HDD J Burns <burns@nospam.com> - 2018-11-11 12:39 -0500
Re: APFS on HDD Your Name <YourName@YourISP.com> - 2018-11-12 09:10 +1300
Re: APFS on HDD J Burns <burns@nospam.com> - 2018-11-11 19:26 -0500
Re: APFS on HDD Your Name <YourName@YourISP.com> - 2018-11-12 16:20 +1300
Re: APFS on HDD J Burns <burns@nospam.com> - 2018-11-12 01:46 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-14 02:05 +1300
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-11 07:13 +0000
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-12 02:10 -0500
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-12 02:02 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-12 21:57 +1300
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-12 18:26 -0500
Re: APFS on HDD Jolly Roger <jollyroger@pobox.com> - 2018-11-13 01:12 +0000
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-12 23:44 -0500
Re: APFS on HDD Jolly Roger <jollyroger@pobox.com> - 2018-11-13 18:17 +0000
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-13 19:38 +1300
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-13 10:21 +0000
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-13 05:55 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-14 01:28 +1300
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-13 13:40 +0000
Re: APFS on HDD Jolly Roger <jollyroger@pobox.com> - 2018-11-13 18:18 +0000
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-13 05:57 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-14 01:28 +1300
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-13 13:27 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-14 13:31 +1300
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-14 15:33 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-15 12:04 +1300
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-15 00:35 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-15 22:24 +1300
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-15 12:39 -0500
Re: APFS on HDD Stephen Hoffman <seaohveh@hoffmanlabs.invalid> - 2018-11-16 13:45 -0500
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-16 20:13 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-18 18:37 +1300
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-18 17:40 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-19 13:42 +1300
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-19 02:08 +0000
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-19 15:52 +1300
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-18 22:31 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-20 13:23 +1300
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-19 23:32 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-20 22:05 +1300
Re: APFS on HDD "David B." <"David B"@nomail.afraid.org> - 2018-11-20 09:36 +0000
Re: APFS on HDD André G. Isaak <agisaak@gm.invalid> - 2018-11-20 06:12 -0700
Re: APFS on HDD "David B." <"David B"@nomail.afraid.org> - 2018-11-20 14:28 +0000
Re: APFS on HDD nospam <nospam@nospam.invalid> - 2018-11-20 09:36 -0500
Re: APFS on HDD nospam <nospam@nospam.invalid> - 2018-11-20 08:57 -0500
Re: APFS on HDD "David B." <"David B"@nomail.afraid.org> - 2018-11-20 14:34 +0000
Re: APFS on HDD nospam <nospam@nospam.invalid> - 2018-11-20 09:36 -0500
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-19 05:46 +0000
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-19 02:27 -0500
Re: APFS on HDD Stephen Hoffman <seaohveh@hoffmanlabs.invalid> - 2018-11-19 11:42 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-20 13:23 +1300
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-19 21:57 -0500
Re: APFS on HDD dempson@actrix.gen.nz (David Empson) - 2018-11-20 16:28 +1300
Re: APFS on HDD JF Mezei <jfmezei.spamnot@vaxination.ca> - 2018-11-21 13:24 -0500
Re: APFS on HDD Stephen Hoffman <seaohveh@hoffmanlabs.invalid> - 2018-11-19 11:34 -0500
Re: APFS on HDD Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-11-13 13:41 +0000
Re: APFS on HDD Alan Browne <bitbucket@blackhole.com> - 2018-11-11 13:04 -0500
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