New 24" iMac, External Disk Drives, USB Ports & Time machine....

[UtherRex]

OK I have a new 24" iMac, it's the model that has two Thunderbolt/USB 4 ports and two USB 3 ports. I have an external HDD that I used to use on my previous iMac for Time Machine backups. I bought some USB C adapters and a cable that would plug from USB C straight into the HDD (Micro-B).

When I try and do a time machine backup with the HDD plugged into either of the Thunderbolt 4 ports it does a few MB, gets stuck, the disk is reported as being ejected and then the backup fails.

When I try and do a time machine backup with the HDD plugged into either of the USB 3 ports it seems to work without issue.

I have tried using both the new direct cable and the old cable via a USB C adapter, the results are the same.

The Thunderbolt 4 ports seem to work fine for things like USB headphones (via the USB C adapters) or my iPhone (straight in with its USB C socket). So I don't think it's that the ports are broken. I also managed to format the external HDD using the Thunderbolt Ports.

So what's going on? Is it something to do with the data rate? Is there a different cable that I need? Are my ports actually dodgy and the Mac needs to go back?

I'm glad that I didn't buy the cheaper iMac and have only the Thunderbolt ports, I don't know what I would be doing otherwise. I do have another external HDD that I use for backups but I don't want to test that yet as it has the backups for my previous Mac on them, they'll get wiped when I'm totally happy with this one.

 

[Fishrrman]

"When I try and do a time machine backup with the HDD plugged into either of the Thunderbolt 4 ports it does a few MB, gets stuck, the disk is reported as being ejected and then the backup fails.
When I try and do a time machine backup with the HDD plugged into either of the USB 3 ports it seems to work without issue."

Fishrrman's rule:
When method a doesn't work, but method b DOES,
then...
...Use the method that works for you.

(nothing follows)

 

[xraydoc]

OK I have a new 24" iMac, it's the model that has two Thunderbolt/USB 4 ports and two USB 3 ports. I have an external HDD that I used to use on my previous iMac for Time Machine backups. I bought some USB C adapters and a cable that would plug from USB C straight into the HDD (Micro-B).

When I try and do a time machine backup with the HDD plugged into either of the Thunderbolt 4 ports it does a few MB, gets stuck, the disk is reported as being ejected and then the backup fails.

When I try and do a time machine backup with the HDD plugged into either of the USB 3 ports it seems to work without issue.

I have tried using both the new direct cable and the old cable via a USB C adapter, the results are the same.

The Thunderbolt 4 ports seem to work fine for things like USB headphones (via the USB C adapters) or my iPhone (straight in with its USB C socket). So I don't think it's that the ports are broken. I also managed to format the external HDD using the Thunderbolt Ports.

So what's going on? Is it something to do with the data rate? Is there a different cable that I need? Are my ports actually dodgy and the Mac needs to go back?

I'm glad that I didn't buy the cheaper iMac and have only the Thunderbolt ports, I don't know what I would be doing otherwise. I do have another external HDD that I use for backups but I don't want to test that yet as it has the backups for my previous Mac on them, they'll get wiped when I'm totally happy with this one.

May just be the fault of the external drive (and whatever interface chipset it uses not liking the USB-4 signaling). If it works on the USB-C port, just use it on the USB-C port. If your phone connects and transfers data correctly, then it doesn't sound like the Thunderbolt ports are bad.

 

[4sallypat]

...
I'm glad that I didn't buy the cheaper iMac and have only the Thunderbolt ports, I don't know what I would be doing otherwise. I do have another external HDD that I use for backups but I don't want to test that yet as it has the backups for my previous Mac on them, they'll get wiped when I'm totally happy with this one.

Well I have the "cheaper" M1 iMac (base with 2 ports) and it works perfectly.

I used a Time Machine backup from my 2015 MBP (Catalina) and it transferred perfectly using Migration Assistant into the M1 iMac.

Using a genuine Apple TB3-TB2 adapter (LaCie TB external SSD), USB-C to Mini Display port adapter (24" Cinema display), and a BlackBox USBC2000 dongle for my 3 USB-A where my Apple SuperDrive, SoundBlaster Play3 DAC, and my wired mouse.

 

[macintoshmac]

Well I have the "cheaper" M1 iMac (base with 2 ports) and it works perfectly.

I used a Time Machine backup from my 2015 MBP (Catalina) and it transferred perfectly using Migration Assistant into the M1 iMac.

Using a genuine Apple TB3-TB2 adapter (LaCie TB external SSD), USB-C to Mini Display port adapter (24" Cinema display), and a BlackBox USBC2000 dongle for my 3 USB-A where my Apple SuperDrive, SoundBlaster Play3 DAC, and my wired mouse.
View attachment 1785796

I cannot ignore the real estate wastage that is visible here, despite the new iMac being Retina and multi-K as against 1920x1200.