Hi everyone,

Based on the discussions we'd had on how to speed up the iMacs I was gifted, I went ahead and bought an external SSD on Prime Day. I did a clone of the iMac I want to use the SSD (it is running Snow Leopard) and everything looked fine, but it seems the iMac refuses to boot from the drive/clone.

It doesn't recognize the drive when I hold down the option key at startup, and when I try to use the SSD as an external boot drive on another (newer) iMac, it will show the drive at startup and allow me to start up using it, but won't get past the initial grey Apple screen.

I thought that it could be a problem with this specific model drive, but the reason I bought it was because at least one person said on Amazon that he/she was using it for the exact purpose I got it-- to be able to boot up (speed up) an old iMac--- and that it worked fine for that purpose.

So I'm wondering if I have to do something to "bless" the drive/clone (CCC says it should be bootable though!), or if there is some other software reason why it's not allowing me to boot from it.

TiA

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Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)

Peter,

Need more information:

Which drive did you order?

What format did you use for the drive? Depending on the OS, it should be HFS+ with a GUID partition or APFS with a GUID partition.

Robert

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Robert M
Peter,

Need more information:

Which drive did you order?

What format did you use for the drive? Depending on the OS, it should be HFS+ with a GUID partition or APFS with a GUID partition.

Robert

Robert, Snow Leopard can't boot from APFS and a Mac running Snow Leopard can't create a APFS file system.

...

This is the more information we need:

Make/model iMac that you used for the clone:
Did you erase the SSD using the Disk Utility on the Snow Leopard iMac?
If so, what partition scheme and file-system did you set it up with? (Should be GUID/macOS Extended (Journaled)):
What steps did you take to make the clone, and with what cloning software?

Optional:
Make/model of the second iMac, and what OS is it running?

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Edited 2 time(s). Last edit at 07/19/2024 10:44AM by Tiangou.

Tiangou,

Just caught an error. I wrote:

"Depending on the OS, it should be HFS+ with a GUID partition or APFS with a GUID partition"

I should have said "MacOS Extended with GUID partition or APFS with a GUID partition"

Since the machine is running snow leopard, Peter should reformat the drive as an MacOS Extended with GUID partition drive.

You nailed the questions perfectly.

Robert

Hi guys,

To answer Tiangou's questions, in order:

1) It's an iMac10,1, 3.06Ghz Intel Core 2 Duo.

2) Yes

3) Yes, that's what I used, but see below***

4) Cloned with CCC

*** When I went to double-check the formatting scheme, I happened to notice that there were actually TWO partitions on the drive, not one, with one of the partitions being invisible. The drive was apparently sold that way. I've repartitioned and reformatted, and am now redoing the clone and will report back once I know-- but it's a definite possibility that this was the problem.

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Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)

UPDATE: repartitioning made no difference. The drive is still not recognized at boot by the iMac (and when I hold down the option key, it doesn't show up). On the second iMac, the drive is recognized when I hold down the option key, but I can't boot from it-- it shows the grey Apple screen but doesn't go any further. (The second iMac is a iMac14,1 -- 2.7Ghz Intel Core i5.)

At this point, I'm thinking it's either that CCC is not making a bootable clone (though it claims it is) or that this particular drive doesn't work for booting, despite the Amazon reviewer's comment that he/she used it for this exact purpose.

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Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)

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PeterB
UPDATE: repartitioning made no difference. The drive is still not recognized at boot by the iMac (and when I hold down the option key, it doesn't show up)...

I think you've erased the volume. You haven't erased it at the device-level.

Did you ever see the option to select a GUID partition table?

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Snow Leopard (and some newer systems) sometimes have a problem finding bootable partitions and drives using either the keyboard options or the Startup Disk control panel. I've found a utility called "QuickBoot" that does basically the same thing as the Startup Disk control panel that always seems to work though.

Peter,

To follow up... You need to do a low-level format of the drive, not just erase the partitions.

Another question... What kind of keyboard are you using with the machine? On most - not all - but most non-Apple keyboards, the command key and option key function in reverse until after the machine fully boots. After that, the setting in Keyboard Preferences that lets you swap the keys kicks in and the keyboard functions as a normal Apple keyboard.

So, if you're using a non-Apple keyboard with the machine, you may need to hold the command-key to trigger startup/boot command for changing the startup disk.

Robert



Edited 1 time(s). Last edit at 07/20/2024 05:22PM by Robert M.

I've almost never have to do a low-level format of any disk, SSD or USB when moving it between non-compatible systems. The only time I did have to do this was when I acquired a box full of old SCSI disks that came off a Tandum system which had been formatted with 520 byte blocks; they had to be low-level reformatted for 512 byte blocks before I could use them on non-Tandum systems. (Most utilities that say they provide an option for a low-level format don't give you access to things like that. NetBSD does however because I modified it to deal with the Tandum drives.)

On OS X I just repartition the volume and erase the newly created parition(s). But as others have noted, you have to select a disk structure compatible with the system it will be used on.

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bobinmurphy
I've almost never have to do a low-level format of any disk, SSD or USB when moving it between non-compatible systems. The only time I did have to do this was when I acquired a box full of old SCSI disks that came off a Tandum system which had been formatted with 520 byte blocks; they had to be low-level reformatted for 512 byte blocks before I could use them on non-Tandum systems. (Most utilities that say they provide an option for a low-level format don't give you access to things like that. NetBSD does however because I modified it to deal with the Tandum drives.)

On OS X I just repartition the volume and erase the newly created parition(s). But as others have noted, you have to select a disk structure compatible with the system it will be used on.

You're not trying to make those drives bootable on a Mac.

An out-of-the-box SSD with a Master Boot Record partition table will not be bootable on a Mac. It needs to be wiped from the device-level in the DU to use GUID.

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I will double-check it tomorrow, but I'm 99% sure I did a device-level partitioning with GUID...

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Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)

Quote
Tiangou

You're not trying to make those drives bootable on a Mac.

An out-of-the-box SSD with a Master Boot Record partition table will not be bootable on a Mac. It needs to be wiped from the device-level in the DU to use GUID.

You misunderstood what I was trying to say. There are three types of formatting that need to be done on a disk before it can be used for file storage on any system.

First, the low-level device format. This defines the block size and puts down the markers where the blocks are located on the disk. This is done by the manufacturers now days and there are very few utilities available for the end user to re-format at this level. The main reason is that doing a low-level reformat wipes out the bad block relocation vector tables and many large disks delivered today already have some bad blocks revectored.

Second, the Volume need to be "formatted". This defines the structure of the volume, installs the initial volume boot and defines the location and size of the partitions on the volume. (Many now incorrectly refer to this as a low-level format, but it more correctly is an initialization of the volume.) On Mac there are two volume formats used today, Master Boot Record (MBR) and GUID (which is called GPT on other systems. (Old 68k Macs used a third method called Apple Partition Map or APM.) This operation on a Mac is done in Disk Utility with the device level "partition" option and the user can select either MBR or GUID. On Windows it's done in the Disk Management Control Panel. On Linux and BSD it can be done with utilities like Gpart, Kpart, or at the command line level with fdisk or gpt. On the Mac once the partitions are defined they will show up in DU but they're greyed out and can't be mounted yet because the partition(s) need to be formatted for the file system it will contain.

So the third level of formatting is the partition or file system. This is where the user identifies the type of File System that the partition will hold and formatting here defines the file structure. Once this is done the partition can be seen (for boot or other use) and can be mounted. On the Mac this is done with DU by erasing the partition and the user can select from a variety of supported filesystems HFS/HFS+, Fat/ExFAT, APFS. On Windows the user has fewer options and this is done as part of the partition definition step. On Linux/BSD there are about 3 dozen options for File Systems and File System formatting is done with various versions of mkfs.

For modern Macs the Volume must be GUID (or GPT) if it is to be used for booting. The File System must be HFS/HFS+ for versions of OS X up to about 11.0; for later versions it can be HFS/HFS+ or APFS.

For the disk to be bootable it must have the Volume level boot code (installed in the Volume initialization step) which determines where the secondary boot code is located and transfers to it. On MBR volumes this just selects one of the four primary partitions which was designated when the Volume was created. On GUID or GPT volumes it's a bit more complex and there's actually a small hidden partition that was created by the Volume initializaition step that contains the boot code and various drivers that support the many File Systems the system may support.

Once a Volume format (or initialization) is done the partitions can be viewed using hdutil on the Mac, Disk Management on Windows or fdisk/GPT on Linux or BSD. If the File System format step has been done most of these utilities will also show that information for the partition(s) as well.

One final note here: There are SSDs, SD and MicroSD cards being sold on places like Amazon and eBay that claim to support very large storage and many of these are fake or counterfeit. They often carry warnings that they can't be used on Macs and/or must be formatted a FAT or ExFAT (the assumption being that such a Volume would be MBR not GUID or GPT). The reason is that the device firmware has been hacked to show many more blocks on the device than it actually contains. Since the MBR Volume format only writes to reserved blocks at the beginning the the device, the hack appears to work. But GUID/GPT Volume formatting writes to reserved blocks at the beginning and end of the volume, so this formatting fails on a bogus or defective device. Simple test for a good disk device is to try to do a Volume format in GUID/GPT; if it fails the device is bad or counterfeit. Volume and File System "formats" involve nothing more that writing data to the blocks defined on the device by the low-level formatting which is a hardware/firmware function.



Edited 1 time(s). Last edit at 07/21/2024 08:40AM by bobinmurphy.

Hi all,

I've made sure that the drive was formatted with GUID at the device level. Still no go... it won't boot on the iMac it was cloned from (and isn't recognized with the option key), and the newer iMac will recognize it with the option key but not boot from it (grey Apple screen, won't go forward with booting).

I really doubt a low-level format will solve the problem. Oh, and I also tried doing a PRAM reset, that made no difference either.

Not sure what to try at this point, or if I should just give up, return the drive, and try another.

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Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)

Before returning it, do a clean install of an OS known to run on the iMac in question. If that doesn’t work, take it back.

PeterB,

Just wondering... Which specific external did you purchase? Have you tried swapping out the cable? Crazy as it sounds, a bad drive and even a bad cable can cause the problems you're having with this configuration.

Robert

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Robert M
PeterB,

Just wondering... Which specific external did you purchase? Have you tried swapping out the cable? Crazy as it sounds, a bad drive and even a bad cable can cause the problems you're having with this configuration.

Robert

I thought about that too ... except that the drive seems to function normally otherwise. (I'm using the cable supplied with the drive of course.)

If anyone's curious, here's the drive: [www.amazon.com]

... I'm going to try one or two more things before I return it. One thing I see mentioned in a few places is that these drives which are bus-powered, might not power up quickly enough to be recognized as a boot drive, and also that there may be flakiness by USB port, so it's worth trying a different port and also making sure that nothing else that could be drawing power is attached to the USB ports.

I could also try a fresh install of the OS on the drive as PeterW suggests, but I've tried using either CCC or SuperDuper to make a clone, and have gotten the same results both ways... and I'll eventually want to use a clone anyway.

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Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)

Try connecting it to the USB port after you boot with the option key held down and see startup disk options.

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If the clean install works, you’ve eliminated the drive as the problem and put the spotlight on the cloning process.

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PeterW
If the clean install works, you’ve eliminated the drive as the problem and put the spotlight on the cloning process.

True; anyone know where I can download the installer for Snow Leopard? It'd probably be faster than my trying to find the DVD's...

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Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)

Try this for the installer - [forums.macrumors.com]

PeterB,

SSK is a known brand. Not a big name, mind you, but definitely not an unknown. You shouldn't have issues with delays in powering it up. I actually have one of their SSD sticks:

[www.amazon.com]

I haven't tried turning it into a boot drive yet but I've had no issues at all with it powering up and mounting on the desktop quickly. Been serving as a sneakernet stick quite nicely.

Also have a version from Orico:

[www.amazon.com]

Haven't tried it as a boot stick yet either. Been dandy for the sneakernet, though.

Robert

Thanks everyone. I'm tempted to try making a clone on a USB stick, just to see if THAT works... if it does, then obviously the problem is with the drive...

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Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)