Ignite-UX and SAS white paper

8
Removing a SAS device when there are still devices in higher
numbered bays
In this section we will look at removing SAS devices from a system. We will start with the following
configuration:
SAS Enclosure Bay # Hardware Path
1 0/4/1/0.0.0.0.0
2 0/4/1/0.0.0.1.0
3 0/4/1/0.0.0.2.0
4 0/4/1/0.0.0.3.0
5 0/4/1/0.0.0.4.0
If we remove the device in Bay 3 we will be left with the following configuration:
SAS Enclosure Bay # Hardware Path
1 0/4/1/0.0.0.0.0
2 0/4/1/0.0.0.1.0
Not Present
4 0/4/1/0.0.0.3.0
5 0/4/1/0.0.0.4.0
If you recover the system you will end up with the following configuration:
SAS Enclosure Bay # Hardware Path New Hardware Path
1 0/4/1/0.0.0.0.0 0/4/1/0.0.0.0.0
2 0/4/1/0.0.0.1.0 0/4/1/0.0.0.1.0
Not Present
4 0/4/1/0.0.0.3.0 0/4/1/0.0.0.2.0
5 0/4/1/0.0.0.4.0 0/4/1/0.0.0.3.0
This would cause problems the next time you were to ever cold-install or recover the system. The
new hardware paths cannot be correctly assigned to the disks in bays 4 and 5 because, as of
C.7.10, there is no way for Ignite-UX to arbitrarily move a hardware path. The only method Ignite-
UX can use to correct legacy hardware path assignments is swapping between two disks. So, in
the above example, there is no way to assign the disk in Bay 4 the correct hardware path of
0/4/1/0.0.0.3.0 or the disk in Bay 5 the correct hardware path of 0/4/1/0.0.0.4.0.
Continuing with our scenario, you would probably like to fix the hardware path assignments that
were confused by recovering without an expected device in Bay 3. Starting with our misassigned
hardware paths, place a SAS device into Bay 3 and then recover the system; Ignite-UX will then
swap legacy hardware path assignments until each device has the correct path.
SAS Enclosure Bay # Hardware Path New Hardware Path
1 0/4/1/0.0.0.0.0 0/4/1/0.0.0.0.0
2 0/4/1/0.0.0.1.0 0/4/1/0.0.0.1.0
3 0/4/1/0.0.0.4.0 0/4/1/0.0.0.2.0
4 0/4/1/0.0.0.2.0 0/4/1/0.0.0.3.0
5 0/4/1/0.0.0.3.0
0/4/1/0.0.0.4.0