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pleasehelpthanks

macrumors newbie
Original poster
Sep 21, 2021
10
0
Hi, I brought an imac 2019 21.5" 1tb HDD to a 3rd party repair shop (warranty expired) since I cant install the OS through online recovery or a bootable drive. It just freezes and cant use erase, use first aid or even reinstall the os. The advice was to replace the hard drive. Im planning on replacing it with a 1tb SSD. Do you guys think it's a hard drive problem? Im just starting to read about it but do I also need to install a thermal sensor on this? And after replacing the HD, I can just reformat the SSD through disk utility and install the OS through recovery mode?

I ask this since the shop charges for the labor of replacing the hard drive and a different charge to install the OS. If the OS could easily be installed, I would like to just pay for the HD replacement. I have a usb bootable drive prepared,

The unit was just given to me so I want to try to have it repaired if possible.
 

pleasehelpthanks

macrumors newbie
Original poster
Sep 21, 2021
10
0
No sensor needed, you can just install yourself using internet recovery.
so it's really a hard drive problem? if I cant do the normal recovery? I attempted to delete the files in the computer since the normal erase didnt work. I somehow deleted all the files but the "macintosh HD" is gone and I can still see the hard drive but with a different name. I think just the standard hard drive name now
 

Mr_Brightside_@

macrumors 68040
Sep 23, 2005
3,801
2,170
Toronto
I can't tell you for sure without physically accessing the computer. It sounds like you formatted it incorrectly. Post a photo from Disk Utility if you want more help.
 

pleasehelpthanks

macrumors newbie
Original poster
Sep 21, 2021
10
0
I can't tell you for sure without physically accessing the computer. It sounds like you formatted it incorrectly. Post a photo from Disk Utility if you want more help.
the unit is not with me now but i'll send a photo in a few hours. thank you! but for now, I can only access disk utility via online recovery and thru a bootable disk.
 

pleasehelpthanks

macrumors newbie
Original poster
Sep 21, 2021
10
0
I can't tell you for sure without physically accessing the computer. It sounds like you formatted it incorrectly. Post a photo from Disk Utility if you want more help.
This is the disk utility
 

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pleasehelpthanks

macrumors newbie
Original poster
Sep 21, 2021
10
0
I would try an erase of Apple HDD, format it as APFS/GUID, and see where that takes you. Name it Macintosh HD.
tried this and let it run overnight. 6 hours now and looks like it is stuck. The 2nd picture is when I run first aid
 

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Fishrrman

macrumors Penryn
Feb 20, 2009
29,209
13,272
OP:

Can you answer:
Are you booted to internet recovery?
Or... are you booted from a USB installer?

Referring to the pic you posted in #6 above:

Either boot to internet recovery or from a USB installer and get back to this step.

Seems to me you need to click the TOPMOST line "Apple HDD HTS..."

Then click the "erase" button.
Erase to "APFS, GUID partition format".

Does the drive erase without problems?
If so, I suggest you now run disk utility's "first aid" feature on the drive.
Do you get "a good report"?
If so, I suggest you run the first aid routine 3 or 4 MORE TIMES in succession.
Do you get a good report every time?
If so, sounds like the drive is ok to me.

Now quit disk utility and open the OS installer and start clicking through.

Any better?
 
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name99

macrumors 68020
Jun 21, 2004
2,406
2,301
Hi, I brought an imac 2019 21.5" 1tb HDD to a 3rd party repair shop (warranty expired) since I cant install the OS through online recovery or a bootable drive. It just freezes and cant use erase, use first aid or even reinstall the os. The advice was to replace the hard drive. Im planning on replacing it with a 1tb SSD. Do you guys think it's a hard drive problem? Im just starting to read about it but do I also need to install a thermal sensor on this? And after replacing the HD, I can just reformat the SSD through disk utility and install the OS through recovery mode?

I ask this since the shop charges for the labor of replacing the hard drive and a different charge to install the OS. If the OS could easily be installed, I would like to just pay for the HD replacement. I have a usb bootable drive prepared,

The unit was just given to me so I want to try to have it repaired if possible.

(a) It could well be the hard drive. I've had this happen on at least three occasions. Mostly a hard drive fails in ways that are obvious and gradual, or can be worked around (eg random bad sectors in the middle) but a hard drive can fail in ways that macOS simply not accept and cannot work around. (Maybe no OS can?)
Looks like you have that sort of flaw -- one of the "critical" sectors at the very beginning of the disk has failed and can't be mapped around. Well, it happens!


(b) You don't HAVE to replace the drive. Macs can boot off external USB drives (well, with M1 or even T2 Macs it's a lot trickier but still possible), and it would be much easier to do that and just use that as experiment.
What you want to do is boot via Internet and get to the point where you install the OS on your external USB SSD. Then set that USB SSD as the boot drive and life should be fine from that point on.

I am leaving out steps that I assume are obvious -- the main knowledge you need is simply that
- you can install an OS on an external drive
- you can boot from it
- life works fine in this mode.
Once you've done it enough that you see it works and are comfortable with the new drive, you can use Migration Assistant to reinstall everything from your Time Machine backup onto that external boot drive.

Even a USB2 external SSD feels adequate for booting and running the machine, but if you can get a USB3 drive (or a USB3 enclosure) that's a little bit better of course.


VERY IMPORTANT!!
Check the power rating of your SSD and enclosure. MOST SSD's are specced to run at a little under 4.5W. They will run fine when connected to a USB3 port (which provides 4.5W) but NOT a USB2 port (which provides 2.5W). Symptoms will be that everything seems to work (the drive boots, runs for a few min, but randomly crashes, whenever too many back to back writes exceed the 2.5W f the USB2 port).

Alternative workarounds are to use an enclosure that accepts a power supply, or to use one of those weird double-headed USB cables that have a power connector (red) and a data connector (black) and so can source twice 2.5W.


Depending on what exactly is wrong, every time you boot you might get a warning that macOS cannot read the internal drive. You may be able to format the internal drive to empty space or something else it will ignore; or may just have to live with this. On my iMac I just have to live with it. Every few months when I reboot, I get told there's a drive macOS can't read, I hit the "ignore" button, and that's it, end of story till next reboot.

But apart from that, everything is fine. I have an SSD in a USB3 enclosure, I taped the enclosure to the back of the iMac so it's basically "built-in"; it's stable and out of the way, and the iMac works fine, has been running that way for maybe three years now.
 
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name99

macrumors 68020
Jun 21, 2004
2,406
2,301
(a) It could well be the hard drive. I've had this happen on at least three occasions. Mostly a hard drive fails in ways that are obvious and gradual, or can be worked around (eg random bad sectors in the middle) but a hard drive can fail in ways that macOS simply not accept and cannot work around. (Maybe no OS can?)
Looks like you have that sort of flaw -- one of the "critical" sectors at the very beginning of the disk has failed and can't be mapped around. Well, it happens!


(b) You don't HAVE to replace the drive. Macs can boot off external USB drives (well, with M1 or even T2 Macs it's a lot trickier but still possible), and it would be much easier to do that and just use that as experiment.
What you want to do is boot via Internet and get to the point where you install the OS on your external USB SSD. Then set that USB SSD as the boot drive and life should be fine from that point on.

I am leaving out steps that I assume are obvious -- the main knowledge you need is simply that
- you can install an OS on an external drive
- you can boot from it
- life works fine in this mode.
Once you've done it enough that you see it works and are comfortable with the new drive, you can use Migration Assistant to reinstall everything from your Time Machine backup onto that external boot drive.

Even a USB2 external SSD feels adequate for booting and running the machine, but if you can get a USB3 drive (or a USB3 enclosure) that's a little bit better of course.


VERY IMPORTANT!!
Check the power rating of your SSD and enclosure. MOST SSD's are specced to run at a little under 4.5W. They will run fine when connected to a USB3 port (which provides 4.5W) but NOT a USB2 port (which provides 2.5W). Symptoms will be that everything seems to work (the drive boots, runs for a few min, but randomly crashes, whenever too many back to back writes exceed the 2.5W f the USB2 port).

Alternative workarounds are to use an enclosure that accepts a power supply, or to use one of those weird double-headed USB cables that have a power connector (red) and a data connector (black) and so can source twice 2.5W.


Depending on what exactly is wrong, every time you boot you might get a warning that macOS cannot read the internal drive. You may be able to format the internal drive to empty space or something else it will ignore; or may just have to live with this. On my iMac I just have to live with it. Every few months when I reboot, I get told there's a drive macOS can't read, I hit the "ignore" button, and that's it, end of story till next reboot.

But apart from that, everything is fine. I have an SSD in a USB3 enclosure, I taped the enclosure to the back of the iMac so it's basically "built-in"; it's stable and out of the way, and the iMac works fine, has been running that way for maybe three years now.

Oh, one extra thing. Once you have a boot from an external SSD (so you can experiment more aggressively on the internal drive) look into an app called DriveDx. This will give you a whole lot of SMART details for the internal drive.
It's not perfect, it can't diagnose everything.
But if it tells you "five errors found" and they all look pretty bad, well, that's a fairly solid indicator that that drive is hopeless.
Disk Utility does report "SMART Summary" somewhere on the page for a disk, but it's basically useless compared to DriveDx's level of detail.
DriveDx costs something (IMHO worth paying) but gives you a month of free use before it requires payment.
 
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pleasehelpthanks

macrumors newbie
Original poster
Sep 21, 2021
10
0
OP:

Can you answer:
Are you booted to internet recovery?
Or... are you booted from a USB installer?

Referring to the pic you posted in #6 above:

Either boot to internet recovery or from a USB installer and get back to this step.

Seems to me you need to click the TOPMOST line "Apple HDD HTS..."

Then click the "erase" button.
Erase to "APFS, GUID partition format".

Does the drive erase without problems?
If so, I suggest you now run disk utility's "first aid" feature on the drive.
Do you get "a good report"?
If so, I suggest you run the first aid routine 3 or 4 MORE TIMES in succession.
Do you get a good report every time?
If so, sounds like the drive is ok to me.

Now quit disk utility and open the OS installer and start clicking through.

Any better?
Hi, yes I tried both thru internet and a bootable drive but still when I try to do first aid it gives an error and erase will just be stuck. I had erase running for 6 hours and no change happened. If I just normally turn on the computer without pressing any keys, it will just show me a circle with a slash in the middle. I also tried holding option command P R until the apple logo and loading screen is seen but after that, I still have the same error from first aid and erase
 

pleasehelpthanks

macrumors newbie
Original poster
Sep 21, 2021
10
0
Oh, one extra thing. Once you have a boot from an external SSD (so you can experiment more aggressively on the internal drive) look into an app called DriveDx. This will give you a whole lot of SMART details for the internal drive.
It's not perfect, it can't diagnose everything.
But if it tells you "five errors found" and they all look pretty bad, well, that's a fairly solid indicator that that drive is hopeless.
Disk Utility does report "SMART Summary" somewhere on the page for a disk, but it's basically useless compared to DriveDx's level of detail.
DriveDx costs something (IMHO worth paying) but gives you a month of free use before it requires payment.
Hi, installing an OS in an external hard drive right now. Will try doing that and if works, will try to diagnose the HDD with DriveDx and see the results before I decide to have the HDD replaced. Thank you!
 

pleasehelpthanks

macrumors newbie
Original poster
Sep 21, 2021
10
0
Oh, one extra thing. Once you have a boot from an external SSD (so you can experiment more aggressively on the internal drive) look into an app called DriveDx. This will give you a whole lot of SMART details for the internal drive.
It's not perfect, it can't diagnose everything.
But if it tells you "five errors found" and they all look pretty bad, well, that's a fairly solid indicator that that drive is hopeless.
Disk Utility does report "SMART Summary" somewhere on the page for a disk, but it's basically useless compared to DriveDx's level of detail.
DriveDx costs something (IMHO worth paying) but gives you a month of free use before it requires payment.
Ran DriveDx.
Adv. SMART status: ailing
Overall health rating: Bad 10.5%
Overall performance rating:Good 71.3%
Issues found: 3

seems like I really do have to have the HDD changed
 

Fishrrman

macrumors Penryn
Feb 20, 2009
29,209
13,272
"seems like I really do have to have the HDD changed"

See how much it's going to cost.
If the price seems too high, there's another option.

Get a "blade type" nvme drive. (many different ones available)
Get a USB3.1 gen2 enclosure. (many different ones available)
Put the drive into the enclosure (many just snap together).
Connect to the iMac.
Boot to a special version of internet recovery:
Command-SHIFT-OPTION-R
(if you're connecting via wifi, you'll need your wifi password)
Let the internet utilities load (it will take a little while)

Now, open disk utility
Format the blade SSD to APFS, GUID partition format.
Close disk utility and open the OS installer.
See if you can install a copy of Mojave onto the external SSD.
The iMac will reboot one or more times, and the screen will go dark for a few minutes.
BE PATIENT.
When done, you should have a fresh copy of Mojave to set up on the external SSD.

Do the setup.
When the setup assistant asks if you wish to migrate from another drive, say YES and see if setup assistant can "find" the internal drive.
If it does, transfer stuff over.

Now you can boot and run from the external SSD, and it will actually be faster than booting from an internal platter-based drive (if that's what you had).

Get the OS set up and running.
Now see if the internal drive will mount.
It may "mount up" on the desktop, even if it won't boot.

The point is to "get you running" again, and possibly save your old data (if there's no external backup)...
 
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pleasehelpthanks

macrumors newbie
Original poster
Sep 21, 2021
10
0
"seems like I really do have to have the HDD changed"

See how much it's going to cost.
If the price seems too high, there's another option.

Get a "blade type" nvme drive. (many different ones available)
Get a USB3.1 gen2 enclosure. (many different ones available)
Put the drive into the enclosure (many just snap together).
Connect to the iMac.
Boot to a special version of internet recovery:
Command-SHIFT-OPTION-R
(if you're connecting via wifi, you'll need your wifi password)
Let the internet utilities load (it will take a little while)

Now, open disk utility
Format the blade SSD to APFS, GUID partition format.
Close disk utility and open the OS installer.
See if you can install a copy of Mojave onto the external SSD.
The iMac will reboot one or more times, and the screen will go dark for a few minutes.
BE PATIENT.
When done, you should have a fresh copy of Mojave to set up on the external SSD.

Do the setup.
When the setup assistant asks if you wish to migrate from another drive, say YES and see if setup assistant can "find" the internal drive.
If it does, transfer stuff over.

Now you can boot and run from the external SSD, and it will actually be faster than booting from an internal platter-based drive (if that's what you had).

Get the OS set up and running.
Now see if the internal drive will mount.
It may "mount up" on the desktop, even if it won't boot.

The point is to "get you running" again, and possibly save your old data (if there's no external backup)...
I did this with an external hard drive I had laying around with a bootable usb stick I had of mojave. The imac is currently working so I think I’ll just go with an external drive. Just have to buy an ssd and an enclosure.

Is the bootable usb stick okay to install the OS to the external drive or should I really use the internet recovery route?

edit: i havent done much research yet but will a 3.1 or 3.2 gen 2 usb enclosure maximize the speed of the nvme? With maximum of 10Gbps. I looked into thunderbolt enclosures (max 40Gbps) for the blade type nvme and it will cost me about the same as the actual ssd so I dont think I’ll buy the thunderbolt version.

Will a 1tb 2.5 SATA SSD like samsung 870 EVO be better than a mid range 1tb M.2 nvme ssd? The higher end M.2 nvme like samsung 970 EVO plus or WD black SN750 are a little outside of what Im willing to spend

the imac will just be for normal use, internet browsing/streaming and office work.
 
Last edited:

name99

macrumors 68020
Jun 21, 2004
2,406
2,301
Ran DriveDx.
Adv. SMART status: ailing
Overall health rating: Bad 10.5%
Overall performance rating:Good 71.3%
Issues found: 3

seems like I really do have to have the HDD changed
The real issue is "why bother to change the HDD"?
It will cost a fortune. It will not give you THAT MUCH better performance than an external SSD, especially one in a USB3 enclosure.

It's your money, but honestly I would not spend it that way -- keep the money towards your M3 iMac upgrade in a few years!
 

name99

macrumors 68020
Jun 21, 2004
2,406
2,301
I did this with an external hard drive I had laying around with a bootable usb stick I had of mojave. The imac is currently working so I think I’ll just go with an external drive. Just have to buy an ssd and an enclosure.

Is the bootable usb stick okay to install the OS to the external drive or should I really use the internet recovery route?

edit: i havent done much research yet but will a 3.1 or 3.2 gen 2 usb enclosure maximize the speed of the nvme? With maximum of 10Gbps. I looked into thunderbolt enclosures (max 40Gbps) for the blade type nvme and it will cost me about the same as the actual ssd so I dont think I’ll buy the thunderbolt version.

Will a 1tb 2.5 SATA SSD like samsung 870 EVO be better than a mid range 1tb M.2 nvme ssd? The higher end M.2 nvme like samsung 970 EVO plus or WD black SN750 are a little outside of what Im willing to spend

the imac will just be for normal use, internet browsing/streaming and office work.

Honestly, a gen 3 enclosure (with UASP) and an 2.5" SSD is just fine. Anything beyond that is paying a lot for bragging rights (and you have to start being careful about power draw...)

Something super basic like this: https://www.amazon.com/Sabrent-Tool-free-Enclosure-Optimized-EC-UASP/dp/B00OJ3UJ2S/
is probably fine. (I'd recommend the brand I bought, but that's so old it doesn't even exist on Amazon any more)

As for the drive, Samsung seems to be the best choice for low drama, probably works without hassle, probably going to be reliable (unless AMZ ships you a counterfeit -- always gave to be careful of that!) and cheap enough that it's not worth trying to save a few dollars and get cheaper.

The realistic options are an EVO 860 (about $150 for 1TB) or a QVO 870 (about $110 for 1TB. That's QLC SSD, so slower, and shorter lifespan. But be realistic here. How aggressively do you use your SSD, and how long do you plan to keep using it? Probably you won't care about this drive in three years when you get a new mac...)
But you know your budget better than me!

An additional option to consider is
- either getting a smaller SSD OR, if you use most of the 1TB of an SSD, augmenting it with
- an SD or SDXC card
You can pop one of these in the back of an iMac, barely see it, and use it for additional storage of things like movies.
SD cards are kinda slow, like USB2 speeds, but crazy cheap.
SDXC are becoming reasonably priced, especially at smaller sizes, something like

and are a great way to just add some additional storage that's fast enough and very easy to work with.
I wouldn't boot off one, but I do use one, as I said, as extra storage for certain categories of items.
 
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