Re: Erasure Coded Pools and PGs

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Hi,

On 17/06/2015 18:04, Garg, Pankaj wrote:
> Hi,
> 
>  
> 
> I have 5 OSD servers, with total of 45 OSDS in my clusters. I am trying out Erasure Coding with different K and m values.
> 
> I seem to always get Warnings about : Degraded and Undersized PGs, whenever I create a profile and create a Pool based on that profile.
> 
> I have profiles with K and M value pairs : (2,1), (3,3) and (5,3).

By default the crush ruleset for an erasure coded pool needs as many hosts as k+m. I.e. you need 6 hosts for (3,3) and 8 for (5,3). You can change this by setting the failure domain when creating the erasure code profile as documented at

http://docs.ceph.com/docs/master/rados/operations/erasure-code-jerasure/

> 
> What would be appropriate PG values? I have tried from as low as 12 to 1024 and always get the Degraded and Undersized PGs. This is quite confusing.
> 
>  

If the problem is different, it would be great if you could file a bug report with details. The ceph report command will output all the relevant information.

Cheers

> 
> Thanks
> 
> Pankaj
> 
> 
> 
> _______________________________________________
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> ceph-users@xxxxxxxxxxxxxx
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> 

-- 
Loïc Dachary, Artisan Logiciel Libre

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