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

Loic Tortay tortay at cc.in2p3.fr
Mon Dec 19 17:49:05 GMT 2016


On 12/19/2016 05:43 PM, Buterbaugh, Kevin L wrote:
> 
> Right - that’s what I meant by having the proper device name for the NSD from the NSD server you want to be primary for it.  Thanks for confirming that for me.
> 
> This discussion prompts me to throw out a related question that will in all likelihood be impossible to answer since it is hardware dependent, AFAIK.  But in case I’m wrong about that, I’ll ask.  ;-)
> 
> My method for identifying the correct “/dev” device to pass to mmcrnsd has been to:
> 
> 1.  go down to the data center and sit in front of the storage arrays.
> 2.  log on to the NSD server I want to be primary for a given NSD.
> 2.  use “fdisk -l” to get a list of the disks the NSD server sees and eliminate any that don’t match with the size of the NSD(s) being added.
> 3.  for the remaining disks, run “dd if=/dev/<whatever of=/dev/null bs=512k count=1000” against them one at a time and watch to see if the lights for the NSD I’m interested in start blinking.
> 
> Is there a better way?  Thanks...
> 
Hello,
We use device mapper/multipath to assign meaningful names to devices
based on the WWN (or the storage system "volume" name) of the LUNs.
We use a simple naming scheme ("nsdDDNN", where DD is the primary server
number and NN the NSD number for that node, of course all NSDs are
served by at least 2 nodes).

When possible, these names are also used by the storage systems
(nowadays mostly LSI/Netapp units). We have scripts to automate the
configuration of the LUNs on the storage systems with the proper names
as well as for creating the relevant section of "multipath.conf".

There is no ambiguity during "mmcrnsd" (or no need to use "mmchnsd"
later on) and it's also easy to know which filesystem or pool is at risk
when some hardware fails (CMDB, etc.)


Loïc.
-- 
|       Loïc Tortay <tortay at cc.in2p3.fr> - IN2P3 Computing Centre      |



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