Re: Erasure Coding: Determine location of data and coding chunks

[Jonas Jaszkowic <jonasjaszkowic.work@xxxxxxxxx>]

Thank you! I already knew about the ceph osd map command, but I am not sure how to interpret the output. For example, on the described

erasure coded pool, the output is:

osdmap e30 pool 'ecpool' (1) object 'sample-obj' -> pg 1.fa0b8566 (1.66) -> up ([1,4,2,0,3], p1) acting ([1,4,2,0,3], p1)

This basically tells me that the object 'sample-obj‘ is located on pg 1.fa0b8566 (1.66) and has it’s chunks stored on OSDs [1,4,2,0,3].

But I cannot tell where the data chunks and where the coding chunks  are stored, can I? Or is the order of the OSDs in the 

[1,4,2,0,3] list of relevance? I am missing some documentation on how to interpret the output, I guess.

- Jonas

Am 19.06.2017 um 23:45 schrieb Marko Sluga <marko@xxxxxxxxxxxxxx>:

Hi Jonas,

ceph osd map [poolname] [objectname] 

should provide you with more information about where the object and chunks are stored on the cluster.

Regards,

Marko Sluga

Independent Trainer

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W: http://markocloud.com

T: +1 (647) 546-4365

L + M Consulting Inc.

Ste 212, 2121 Lake Shore Blvd W

M8E 4E9, Etobicoke, ON

---- On Mon, 19 Jun 2017 14:56:57 -0400 Jonas Jaszkowic <jonasjaszkowic.work@xxxxxxxxx> wrote ----

Hello all, I have a simple question:

I have an erasure coded pool with k = 2 data chunks and m = 3 coding chunks,

how can I determine the location of the data and coding chunks? Given an object A

that is stored on n = k + m different OSDs I want to find out where (i.e. on which OSDs)

the data chunks are stored and where the coding chunks are stored.

Thank you!

- Jonas

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