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Disk definition order

PostPosted: Sat Jul 29, 2017 11:55 am
by Roland
While testing a SCSI controller with Ubuntu 16.04, I noticed some strange things concerning disk definition order...

Examples of different disk compositions  and their 'sdx' definitions after booting:

1)
Sata HD -> sda
USB disk -> sdb

2)
SCSI HD -> sda
USB disk -> sdb
Sata HD -> sdc

3)
SCSI CD-ROM (no sdx definition given)
USB disk -> sda
Sata HD -> sdb

So, what is the logic in these results...? Why adding a SCSI disk (even when there is no sdx definition given to it) seems to reverse the defintion order of Sata and an USB disks? This is not just a curiosity because if the sdx definition of your boot disk changes you get Kernel panics and have to change Bootargs...

( I do not dare even guess what might happen if also an additional Sata controller would be present! ;) )