[gpfsug-discuss] translating /dev device into nsd name

Mon Dec 19 15:30:58 GMT 2016

Indeed. It only matters when deploying NSDs. Post-deployment, all luns 
(NSDs) are labeled - and they are assembled by GPFS.

Keep in mind: If you are deploying multiple NSDs (with multiple servers) - 
you'll need to pick one server to work with... Use that server to label 
the luns (mmcrnsd)... In the nsd stanza file - the server you choose will 
need to be the first server in the "servers" list.

Ken Hill
Technical Sales Specialist | Software Defined Solution Sales
IBM Systems 

Phone:1-540-207-7270
E-mail: kenh at us.ibm.com

2300 Dulles Station Blvd
Herndon, VA 20171-6133
United States

From:   "Daniel Kidger" <daniel.kidger at uk.ibm.com>
To:     "gpfsug main discussion list" <gpfsug-discuss at spectrumscale.org>
Cc:     "gpfsug main discussion list" <gpfsug-discuss at spectrumscale.org>
Date:   12/19/2016 06:42 AM
Subject:        Re: [gpfsug-discuss] translating /dev device into nsd name
Sent by:        gpfsug-discuss-bounces at spectrumscale.org

Valdis wrote:
Keep in mind that if you have multiple NSD servers in the cluster, there
is *no* guarantee that the names for a device will be consistent across
the servers, or across reboots.  And when multipath is involved, you may
have 4 or 8 or even more names for the same device....

Indeed the is whole greatness about NSDs (and in passing why Lustre can be 
much more tricky to safely manage.)
Once a lun is "labelled" as an NSD then that NSD name is all you need to 
care about as the /dev entries can now freely change on reboot or differ 
across nodes. Indeed if you connect an arbitrary node to an NSD disk via a 
SAN cable, gpfs will recognise it and use it as a shortcut to that lun.

Finally recall that in the NSD stanza file the /dev entry is only matched 
for on the first of the listed NSD servers; the other NSD servers will 
discover and learn which NSD this is, ignoring the /dev value in this 
stanza.

Daniel

IBM Spectrum Storage Software
+44 (0)7818 522266
Sent from my iPad using IBM Verse

On 17 Dec 2016, 21:43:00, Valdis.Kletnieks at vt.edu wrote:

From: Valdis.Kletnieks at vt.edu
To: gpfsug-discuss at spectrumscale.org
Cc: 
Date: 17 Dec 2016 21:43:00
Subject: Re: [gpfsug-discuss] translating /dev device into nsd name

On Fri, 16 Dec 2016 23:24:34 -0500, Aaron Knister said:
> that I can then parse and map the nsd id to the nsd name. I hesitate
> calling ts* commands directly and I admit it's perhaps an irrational
> fear, but I associate the -D flag with "delete" in my head and am afraid
> that some day -D may be just that and *poof* there go my NSD 
descriptors.
Others have mentioned mmlsdnsd -m and -X
Keep in mind that if you have multiple NSD servers in the cluster, there
is *no* guarantee that the names for a device will be consistent across
the servers, or across reboots.  And when multipath is involved, you may
have 4 or 8 or even more names for the same device....
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