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

[Daniel Kidger]

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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