Re: How To Get WWN and Device Mapping

[Douglas Gilbert <dgilbert@interlog.com>]

Paul,
Does 'lsscsi -tL' give you what you want in the
node_name entry?

That is for the target, 'lsscsi -tHL' would be for
the initiator.

Doug Gilbert


Paul Lung (paul.lung@loglogic.com) wrote:
> Hi James,
> 
> Thank you for the reply. I'm actually looking for the WWN. The reason is I want to setup multipath, and for that I would want to know which mapped devices on my linux box actually point to the same disk. The disk array I'm using for multipath has two controllers, and therefore two WWPNs. So using WWPN would not work for this purpose.
> 
> Paul Lung
> 
> -----Original Message-----
> From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com] 
> Sent: Friday, June 19, 2009 5:21 PM
> To: Paul Lung (paul.lung@loglogic.com)
> Cc: linux-scsi@vger.kernel.org
> Subject: Re: How To Get WWN and Device Mapping
> 
> On Fri, 2009-06-19 at 16:54 -0700, Paul Lung (paul.lung@loglogic.com)
> wrote:
>> Hi,
>>
>> I'm using 2.6.25.14 kernel with the qla2xxx driver turned on for a
>> SAN, and I tried to use SCLI from QLogic to get the linux device->wwn
>> mapping. However, SCLI does not seem to be able to detect any LUNs
>> with the driver in 2.6.25 kernel.
> 
> You'll need to ask qlogic about their tools.
> 
>>  I then found that doing a scsi_id on a device(say, ./block/sde)  will
>> give me the wwn, with an extra number in the front.
> 
> man scsi_id will tell you what this is and why it's there.
> 
>>  However, further research seems to indicate that scsi_id does not
>> always give back the wwn. It's is totally dependent on the physical
>> device being queried. 
> 
> For WWN this is true ... the device must export it properly via the
> correct VPD inquiry for it to be displayed ... although most fibre
> devices do nowadays.
> 
>> So, is there any way to reliably get the WWN of a linux device? The
>> qla2xxx driver must have gotten the wwn of all the drives on the SAN.
>> Is this information "published" anywhere?
> 
> I think you're confusing WWN and WWPN ... it's the latter the fibre has
> to know. If it's the WWPN you're after, it's the fc_transport port_name
> attribute (either of the rport or the target).
> 
> James
> 
> 
>> Thank you very much for your time.
>>
>> Paul Lung--
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