Wonder if anyone can help with this issue please.
My late 2013 iMac i5 is running Catalina and has been booting up and running fine from a little external (USB) SSD drive I fitted a while ago - Panasonic APS-XS03 480GB NAND. I obtained an identical new SSD this week and wanted to use it via USB as a spare drive for storing photos. However whenever the 2nd SSD is plugged in the iMac has serious issues, namely it takes ages to bootup and then just seems unable to do anything without a long spinning beechball, basically it is so slow it is unusable.
Unplug the 2nd drive and all goes back to normal speedy bootup and use.
New SSD was erased with Disk Utility as APFS and is recognised in Finder, original external SSD still shows fine as startup disk.
My late 2013 iMac i5 is running Catalina and has been booting up and running fine from a little external (USB) SSD drive I fitted a while ago - Panasonic APS-XS03 480GB NAND. I obtained an identical new SSD this week and wanted to use it via USB as a spare drive for storing photos. However whenever the 2nd SSD is plugged in the iMac has serious issues, namely it takes ages to bootup and then just seems unable to do anything without a long spinning beechball, basically it is so slow it is unusable.
Unplug the 2nd drive and all goes back to normal speedy bootup and use.
New SSD was erased with Disk Utility as APFS and is recognised in Finder, original external SSD still shows fine as startup disk.