LSI 3008 based HBA (mpr) and backplane slot identification

[Alan Somers]

On Thu, Jun 4, 2015 at 9:33 AM, Borja Marcos <borjam at sarenet.es> wrote:
>
> On Jun 4, 2015, at 5:23 PM, Alan Somers wrote:
>
>> I've never used sas3ircu or sas2ircu, but it's probably getting the
>> slot number based on either the expander's SES Additional Element
>> Status Page, or by the expander's SMP DISCOVER response.  Both of
>> those methods will give stable responses.  Even if you swap drives,
>> move them around, turn phys on and off, etc, both of those methods
>> will still map the same physical slot to the same Slot # every time.
>> Only an expander or HBA firmware upgrade can change it.  However, the
>> slot mapping may not make intuitive sense.  You'll have to experiment
>> to see what Slot # corresponds to what physical slot.
>
> Thank you very much. At least on the machines on which I am using it, the mapping is
> stable and even intuitive.
>
> What I was wondering was it something could change the mapping unexpectedly.
> Understood, a firmware update is a risk, but I was thinking about those static mappings
> between target IDs and particular disks (I imagine, serial numbers) kept by the HBA. It
> would be a tickling timebomb if, say, after four or five disk replacements numbers begun
> to get shuffled.


Nope.  Slot stuff happens at a lower layer than bus/target/lun
assignment.  For each slot, the expander tells the host the SAS
Address of the drive installed in that slot, if any.  If you want to
play around, install sysutils/sg3_utils and run "sg_ses -p 10
/dev/ses0".


>
>> When you need to replace a drive, your best option would be to use the
>> "sas3ircu locate" command to turn on the slot's error LED.  Then you
>> won't need to consult a slot mapping diagram.
>
> Sorry, I didn't know that command. I haven't been exactly eager to try options to sas[23]ircu
> because it's intended for IR firmware (or that I understand) and I am using IT.
>
>
>
> Thank you very much!
>
>
>
>
> Borja.
>

Glad to help.

-Alan