Fibre Channel (SAN)

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Contributor
Posts: 37
Registered: ‎08-08-2012
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What the meaning of "Device type: Physical Unknown(initiator/target)" ?

Why some F-Ports of HBAs are always displayed as Device type: Physical Unknown(initiator/target) via nszonemember, mainly for AIX platform ? 

Contributor
Posts: 45
Registered: ‎06-04-2012

Re: What the meaning of "Device type: Physical Unknown(initiator/target)" ?

What is the HBA speed and FOS version of switch? Generally we find this issue on 2G and 4G.
Contributor
Posts: 37
Registered: ‎08-08-2012

Re: What the meaning of "Device type: Physical Unknown(initiator/target)" ?

4Gbps、FOS 6.x/7.x!   But  I  think it should be nothing to do with those!

 

Contributor
Posts: 31
Registered: ‎05-26-2010

Re: What the meaning of "Device type: Physical Unknown(initiator/target)" ?

[ Edited ]

The device type information will typically show "initiator", "target" or both (Initiator/Target)" and is

dependent upon the attaching device (host adapter f/w, driver) providing such information during

the login processes into the SAN switch.  If this information is not shared with the SAN switch it

is not uncommon for the SAN switch to query the attached device's adapter for such information. 

But again, it will be up to the attaching device's adapter provided this information. 

 

For example,  IBM AIX is known not to provide such information and the result is "nsshow -t", while IBM Storwize registers as both because the adapter is a target for hosts and an initiator for backend storage.

 

IBM AIX server

N    01c8c0;      3;10:00:00:90:fa:a9:a5:28;20:00:00:90:fa:a9:a5:28; na
    Fabric Port Name: 20:dc:00:05:1e:51:d1:01
    Permanent Port Name: 10:00:00:90:fa:a9:a5:28
    Device type: Physical Unknown(initiator/target)  <==============
    Port Index: 220
    Share Area: Yes
    Device Shared in Other AD: No
    Redirect: No
    Partial: No
    LSAN: No

 

 

IBM Storwize

 N    01c840;      3;50:05:07:68:02:10:e5:18;50:05:07:68:02:00:e5:18; na
    FC4s: FCP
    Fabric Port Name: 20:de:00:05:1e:51:d1:01
    Permanent Port Name: 50:05:07:68:02:10:e5:18
    Device type: Physical Initiator+Target  <========== !!!
    Port Index: 222
    Share Area: Yes
    Device Shared in Other AD: No
    Redirect: No
    Partial: No
    LSAN: No

The comments and advise included are the author's and do not mirror the views and opinions of any company. Any comments, advise, statements or references are without warranty, liability or claims of expertise. You should seek the assistance of the professional entity for subject matter being pursued.
Regular Contributor
Posts: 164
Registered: ‎02-05-2014

Re: What the meaning of "Device type: Physical Unknown(initiator/target)" ?

Be aware that this is not 100% a Fibre-Channel feature. The concept of initiators and targer is based on SCSI and for Fibre-channel to be able to hook into this it is the FCP (FC Layer 4) that may or maynot take advantage of this.


The FCP protocol has a few service parameters reserved in the PRLI (Process Login) which is a SCSI session initiation between the initiator and target. Two bits of these can be set based on the function that device or service entity has. So in word 3 bits 4 and 5 of that PRLI the HBA or storage-array  driver may set one of these depending on which function it supports.


Now I did mention that the FC switches themselves do not talk SCSI so a provision was made to enable a device to register so called FC4 features. Two of these feature are again bits indicating a target or initiator of both option. This is however optional and as such there is no obligation from any vendor to actually put effort in to support this so in many cases, primarlily older firmware/drivers, you won't see this line in the nameserver.


So Brocade (and Cisco) do a bit of an artificial process of trying  to log in to the remote device as soon as the device has completed its PLOGI. If that succeeds it can do a reverse PRLI to see if it is able to obtain this info. It does however require the HBA to support this and an array port should not have any form of authorisation restrictions enabled otherwise this will fail as well.


So name of the game is to keep firmware and drivers up to date which give you the best chance to get the best bang for your buck.

Kind regards,
Erwin van Londen
Brocade Distinguished Architect
http://www.erwinvanlonden.net The Fibre Channel blog



Q&A -> https://hackhands.com/elo/


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