[gpfsug-discuss] dssgmkfs.mmvdisk number of NSD's

[Andrew Beattie]

Jonathan,

You need to create vdisk sets which will create multiple vdisks, you can then assign vdisk sets to your filesystem. (Assigning multiple vdisks at a time)

Things to watch - free space calculations are more complex as it’s building multiple vdisks under the cover using multiple raid parameters

Also it’s worth assuming a 10% reserve or approx - drive per disk shelf for rebuild space 



Mmvdisk vdisk set ... insert parameters

https://www.ibm.com/support/knowledgecenter/mk/SSYSP8_5.3.2/com.ibm.spectrum.scale.raid.v5r02.adm.doc/bl8adm_mmvdisk.htm

Sent from my iPhone

> On 1 Mar 2021, at 21:45, Jonathan Buzzard <jonathan.buzzard at strath.ac.uk> wrote:
> 
> On 01/03/2021 09:08, Luis Bolinches wrote:
>> Hi
>> 
>> There other reasons to have more than 1. It is management of those. When 
>> you have to add or remove NSDs of a FS having more than 1 makes it 
>> possible to empty some space and manage those in and out. Manually but 
>> possible. If you have one big NSD or even 1 per enclosure it might 
>> difficult or even not possible depending the number of enclosures and FS 
>> utilization.
>> 
>> Starting some ESS version (not DSS, cant comment on that) that I do not 
>> recall but in the last 6 months, we have change the default (for those 
>> that use the default) to 4 NSDs per enclosure for ESS 5000. There is no 
>> impact on performance either way on ESS, we tested it. But management of 
>> those on the long run should be easier.
> Question how does one create a none default number of vdisks per 
> enclosure then?
> 
> I tried creating a stanza file and then doing mmcrvdisk but it was not 
> happy, presumably because of the "new style" recovery group management
> 
> mmcrvdisk: [E] This command is not supported by recovery groups under 
> management of mmvdisk.
> 
> 
> 
> 
> JAB.
> 
> -- 
> Jonathan A. Buzzard                         Tel: +44141-5483420
> HPC System Administrator, ARCHIE-WeSt.
> University of Strathclyde, John Anderson Building, Glasgow. G4 0NG
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