Question 1:

Suppose my computer have two SCSI cards and two SCSI HDs.
1st SCSI HD is on 1st SCSI card and 2nd SCSI HD is on 2nd SCSI card.

according to devices.txt :
(0-15) sda~sdp , major=8

(16-31) sdq~ sdaf , major=65

How 2nd SCSI HD on 2nd SCSI card should mount device file ?
Mount sdb or sdq ?

My idea is "sdq" mounted because different SCSI cards have
different major number which represents a driver.

Major number =8 controls HDs on first SCSI card and major number=65 controls HDs on second SCSI card.

Is My idea correct ?

Question 2:

Normally, common computer have two IDE controllers.
My IDE HD connects with 2nd IDE interface , but 1st IDE connects with
other devices.

according to devices.txt :
22 block Second IDE hard disk/CD-ROM interface
0 = /dev/hdc Master: whole disk (or CD-ROM)
64 = /dev/hdd Slave: whole disk (or CD-ROM)

How IDE HD should mount device file ?
Mount hda or hdc ?

My HD is on 2nd IDE interface and I should mount "hdc" .
However , "hdc" represent third HD and I just have one HD,
so I should mount hda that represents first HD.

Should I mount hda or hdc ??

Thanks for everybod's reply.