With Seagate 4 TB 2,5" HDD. First remove old and connect temp new 4TB HDD.
Then reset HAP-Z1. Sony format HDD with MBR like 2TB and you see 1,7 TB free. Second remove new 4TB HDD from Sony and connect to PC with Windows. Use internal s-ata or USB case. Then with software Paragon Hard Disk Manager 15 Suite convert 4TB to GPT disc. Sony make two HDD volume. One 3GB for maser.db and second for storage (1,7TB) You must add rest of your 4TB HDD to second volume. On second volume right mouse button to Move/Resize volume and then pull right till maximum. So you make second volume from 1,7TB to 3,6TB. Free space before and after must set to 0. Then Yes button and APPLY top button. Wait ca.30 min. Your new HDD is ready. Connect to Sony again this is all. With Paragon_ExtFS_for_Windows_2.1.440 you can read and write music direct to Sony Linux HDD Ext4 on your Windows PC. After then rescan HDD in Sony.
I have also connect another external USB HDD 4 TB Seagate. Work great.
