Before I started the installation I used diskpart to check which drive was the C: drive. Diskpart said the C: drive was disk 2. However in the Windows installation this drive is now "Drive 6".
Isso é simples porque você está tentando comparar uma lista de discos que estão sendo enumerados pelo Windows com uma lista de discos enumerados pelo BIOS / UEFI.
The BIOS may or may not enumerate disks in a specific order. There is no direct relationship between the BIOS order, and the order in which Windows numbers the disks.
Depois que o Windows assumir o controle, aplica-se o seguinte.
During startup, Windows switches from using the BIOS INT13 support to native Windows drivers to access disks. Windows waits for several seconds for the system disk to enumerate through Plug and Play. When there is a match within the time-out period, normal startup will proceed.
The disk numbers that are assigned by Windows after it switches to native Windows storage controller drivers during startup are dependent solely on the order in which the disks are enumerated and processed by Plug and Play. Windows will enumerate available fixed disks, followed by removable disks, assuming that the correct native Windows drivers are already present and installed on the system.
how can I check this beforehand?
Você pode verificar as configurações de firmware para determinar a ordem, pois a enumeração de disco do WinPE (Ambiente de Pré-instalação do Windows) seria baseada na ordem fornecida pelo BIOS / UEFI não no método de inicialização do Windows no estágio de seleção de disco do procedimento de instalação .
Origem: aqui