Late 2012 27" iMac - not recognising new internal HD

[PMQ]

Just installed a new internal 4TB HDD + OWC Temp Sensor in a Late 2012 27" iMac; with High Sierra.

Drive seems to be purring away quite happily - so hopefully physical install OK.

However new drive is not showing in Disc Utilities.

So I need some #101 Terminal command line advice.

'diskutil list' - produces the attached list.

1. Do I use disk1 or disk2?
2. And what are the required Terminal commands to put things to right?

Thanks in advance for any help.

 

[Fried Chicken]

What's the size of the installed disk?

 

[mbosse]

Just installed a new internal 4TB HDD + OWC Temp Sensor in a Late 2012 27" iMac; with High Sierra.

Drive seems to be purring away quite happily - so hopefully physical install OK.

However new drive is not showing in Disc Utilities.

So I need some #101 Terminal command line advice.

'diskutil list' - produces the attached list.

1. Do I use disk1 or disk2?
2. And what are the required Terminal commands to put things to right?

Thanks in advance for any help.

This appears like only the FusionDrive part (128GB) of your iMac is showing? One reason for all you describe could be that you installed the power cable to the new hard drive correctly, but not the data cable.