Fix SCSI max disk limit to support PVSCSI controller capacity

[Dwayne75]

Summary

• The SCSI disk unit number validation, bus/unit mapping in assignDisk(), and reverse mapping in findControllerInfo() all hardcoded 15 usable units per controller, which is only correct for LSI Logic / LSI Logic SAS controllers
• PVSCSI (ParaVirtual) controllers support 64 devices per controller (63 usable after reserving one for the controller)
• Added scsiUsableUnitsPerController() helper that returns the correct limit based on scsi_type, and updated DiffGeneral, assignDisk, and findControllerInfo to use it

Test plan

• Verify existing LSI Logic / LSI Logic SAS configurations still enforce the 15 units-per-controller limit
• Verify PVSCSI configurations now allow up to 63 units per controller
• Verify disk assignment correctly maps unit numbers to controllers for both SCSI types
• Confirm error messages include the SCSI controller type for easier debugging

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Updates SCSI disk unit-number validation and controller/unit mapping so that PVSCSI controllers can use their full supported device capacity (63 usable slots per controller), instead of being limited to the LSI Logic/SAS default (15 usable).

Changes:

• Add scsiUsableUnitsPerController(scsi_type) helper to determine per-controller usable unit capacity.
• Update DiffGeneral() SCSI unit-number maximum validation to use the computed usable-unit limit and include scsi_type in the error message.
• Update SCSI bus/unit mapping in assignDisk() and reverse mapping in findControllerInfo() to use the computed usable-unit limit.

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[Copilot]

Pull request overview

Updates SCSI disk unit-number validation and controller/unit mapping so the provider correctly supports PVSCSI’s larger device capacity (63 usable disk slots per controller vs 15 for LSI Logic / LSI Logic SAS).

Changes:

• Add scsiUsableUnitsPerController(scsiType) helper to centralize per-controller usable slot limits.
• Update DiffGeneral(), assignDisk(), and findControllerInfo() to use the new per-SCSI-type usable unit count instead of a hardcoded 15.
• Add a unit test covering scsiUsableUnitsPerController() for PVSCSI and LSI controller types.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
vsphere/internal/virtualdevice/virtual_machine_disk_subresource.go	Replaces hardcoded SCSI unit math with SCSI-type-aware limits across validation, assignment, and reverse mapping.
vsphere/internal/virtualdevice/virtual_machine_disk_subresource_test.go	Adds unit test for the new helper that returns per-controller usable SCSI slots.

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[spacegospod]

Hey @Dwayne75 thanks for your contribution.

There's a couple of items in the backlog specifically about SCSI controllers and max devices.
#2086
#1427

Please make sure to run all acceptance tests for r/virtual_machine and add new ones that cover your functionality.
Be especially careful for cases such as VMs with a mix of controllers, a mix of scsi controllers only, cloning and importing.

[Dwayne75]

hey @spacegospod, I fixed that issue mentioned by copilot, I ran all the tests I can, my vsphere is a very controlled environment and I do not currently have the ability to run the full acceptance tests.

[Dwayne75]

#1427 my PR should address this one from what I can tell. #2086 this seems to be a different problem related to the id 7 reservation my PR does not fix or make this worse.

[Dwayne75]

hmm also the documentation I can find says it supports 64 addresses with 7 being reserved. However I can clearly set a disk with unit id 64 in the UI.....

So now I am not sure if it actually supports 63 or 64 total disks.