Hello and welcome.
Sorry for the delayed response.
Apple doesn't publish detailed hardware/chip specifications, so it may be hard to determine which model ASMedia controller chip they are using. I don't have any experience with SATA port multipliers personally, and don't believe Apple publishes any information about what optional features of the SATA standard they have implemented/disabled.
I do know that older Mac Pro on-board SATA connectors are not hot-swappable. Not sure about the current model.
Sorry I don't have a better response.
C
Thank you for your response.
The easiest way to determine the model is by physically looking at it if it is located on the underside of the logic board and reading the ASM model printed on the packaging unless the controller IP (intellectual property) has been licensed to be and implemented on the Apple
M2 Ultra SoC itself, in which case only extracting device strings from terminal commands or other programmatic methods would be the only way to positively identify the model.
Other than looking at device feature strings, trying them would be the only way to determine if the optional features such as hot plug and unplug and port multiplier support has been disabled and if not what kind (Command based switching or FIS-based switching) is implemented.
A port multiplier hub is nearly identical in function and analogous to a USB hub or a SAS (Serial Attached SCSI) expander or SAS switch: it lets you attach up to 5 drives to a single port by giving you 5 additional SATA device ports from every 1 on the controller it is plugged into.
I have a Silicon Image SiI 3726 based eSATA II (external SATA II) port multiplier hub and it worked like a charm: I could connect BD-RE DL (Blu-ray Disc REwritable Dual Layer) drives and SATA II / 6 Gb/s hard disk drives in external enclosures and I also had a Silicon Image SiI 4726 Steel Vine eSATA II port multiplier 5-bay hard disk drive enclosure which allowed me to plug in up to 5 internal SATA II / 6 Gb/s hard disk drives mounted on drive carrier sleds into it also worked wonderfully.
The only thing I wish I had was an eSATAp (power over eSATA) II or 6 Gb/s port multiplier hub which would allow me to plug in hard disk drives in an eSATAp enclosure that used a single eSATAp cable for both SATA data and power on the same cable, but that would have required it to also be a USB hub with a USB connection to the host unless possibly plugged into an eSATAp host, controller port, which also doubled as a USB host port allowing USB hubs to be plugged into the eSATAp port as if it were just any other USB host port, which is the physical manner in which power is delivered to eSATAp devices via eSATAp ports and cables.
