Dead SSD, to be replaced on High Sierra

[mdubois]

Hi,

I've got a MacBook Air from mid 2013, my 512SSD is dead and I need to replace it.
The only one available in the shop around the corner is a Transcend 850, that needs at least High Sierra to be recognized.
I've got the following question :
If I'm booting the Macbook Air on an external HDD, I can install OS (I think original one was Mountain Lion), then proceed to the upgrade to High Sierra on this external HDD. Will it be fine then to install the SSD on the machine, and will it be recognized ?
I think High Sierra is required for a firmware issue, and I don't know if doing the installation first on an external HDD will do this upgrade.
Many thanks for your help

Michel

 

[treekram]

The likely reason why High Sierra is required for the Transcend 850 is that it has a 512-byte sector size and earlier OS's that supported PCIe NVMe drives like the Transcend 850 want a 4K sector size.

If you have Mountain Lion on a HDD and then upgrade to High Sierra on the HDD, you should be able to then install on the Transcend 850. However, I think that once you use the installer app, say to upgrade from Mountain Lion to High Sierra on the HDD, the installer app will be deleted so you should copy the installer app before doing the High Sierra upgrade on the HDD. If you already have downloaded the installer app, you can also create a USB installer (although I find installing a new OS to another disk more reliable using a running OS vs. the USB installer).
https://support.apple.com/en-us/HT201372

Note that this will only work if you have the full installer app. In some instances only a small install app is downloaded (it doesn't appear to be clear when/why this happens) in which case you can't create the USB installer as outlined in the instructions above.

In any case, you should format the SSD using Disk Utility before installing the OS on it.

The other wrinkle is that Mojave has just been released so you might want to consider that or if you want High Sierra, if you haven't already downloaded it, it might not be available in the App Store.

 

[ApfelKuchen]

You shouldn't have to install Mountain Lion first. As long as you can boot to Internet Recovery, which that machine certainly can, then you should have the option to install either High Sierra or Mojave right after you format the disk.

 

[mdubois]

Many thanks for your quick replies.
While booting with external HDD, I discover that battery has reached maximum number of cycle and is no longer working properly ... so I will not invest more money in the machine.
Thanks anyway.