I got a windows partition with 30GB. But it needs a lot of maintainance in terms of (cache) cleaning. Depends on what you are planning to do with it.
If you install Windows, using the Boot Camp assistant, and use half of the fusion drive, Windows does not use any of the SSD, and installs only on the spinning hard drive. You cannot choose to use any of the SSD for the Windows installation.
note: the SSD part of a 1TB fusion drive is NOT 128 GB. That is only available on the larger 2 or 3 TB fusion drives. A 1TB fusion drive has a 1TB spinning hard drive, and the SSD device is only 32GB.
You did say in your OP that you have a 1TB fusion drive.
If that is correct, then you have two internal storage devices: a 1TB spinning hard drive, and a 32GB SSD. The two devices are combined by software, and seen as one logical drive.
If you also have a 128GB external SSD, that does not affect the fusion drive, but is just your extra storage space.
This is some inaccurate information.Assuming Fusion drives are like the "hybrid" drives available from Seagate and the like than it is technically one storage device. As in they are not separable from each other in terms of SW. If they are not bonded correctly though they can show as separate volumes by the SW/FW
This is some inaccurate information.
Apple's fusion drives are always two hardware devices (one SSD (flash storage), and one spinning hard drive, joined by software as a single logical volume in a Core Storage setup. A hybrid drive can't be used for a fusion drive, although I suppose if you would connect an SSD to the same Mac that has a hybrid drive, that those two devices could then be fused, and function effectively as a fusion drive. Not sure how the flash memory in the hybrid drive would affect that setup, might work just fine.
You could think of a fusion drive as one storage device, but, more accurately, is a single volume, which is similar to a type of RAID. The OS decides how files are stored on the fusion drive. You don't have any control over either device (you can't decide to manually move files from the SSD to the HDD, for example)
The fusion drive is fairly easy to separate ("Un-bond", if you like that term) through a couple of terminal commands, although the separation means losing any data stored on the logical volume (both devices are erased by the splitting process)
A hybrid drive (SSHD), such as one from Seagate, is a hard drive with flash memory included in the same housing, usually configured as cache for the hard drive. That flash memory can be fairly large, 4 or 8GB. Some hybrid drives, such as the WD Black2 drive, can be configured so the spinning drive is accessed independent of the SSD, even though both use the same connection, and are in the same drive case. I don't think the WD Black2 is compatible with macOS.
Apple does not use a one device hybrid for its fusion drives. All are two devices (Might be SATA, or PCI-E, or one of a couple of other bus protocols that have been used within the last few years for storage). One is a standard spinning hard drive, and the other device is an SSD, each connected to whatever kind of connection is needed. Each device has its own connection, as they are separate physical devices, combined through software into one logical volume - a process you already know about.
A hybrid drive (SSHD), such as one from Seagate, is a hard drive with flash memory included in the same housing, usually configured as cache for the hard drive. That flash memory can be fairly large, 4 or 8GB. Some hybrid drives, such as the WD Black2 drive, can be configured so the spinning drive is accessed independent of the SSD, even though both use the same connection, and are in the same drive case. I don't think the WD Black2 is compatible with macOS.
Apple does not use a one device hybrid for its fusion drives. All are two devices (Might be SATA, or PCI-E, or one of a couple of other bus protocols that have been used within the last few years for storage). One is a standard spinning hard drive, and the other device is an SSD, each connected to whatever kind of connection is needed. Each device has its own connection, as they are separate physical devices, combined through software into one logical volume - a process you already know about.