Re: [SOLVED] Replicated pool with an even size - has min_size to be bigger than half the size?

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Den 2018-03-29 kl. 12:29, skrev David Rabel:
On 29.03.2018 12:25, Janne Johansson wrote:
2018-03-29 11:50 GMT+02:00 David Rabel <rabel@xxxxxxxxxxxxx>:
You are right. But with my above example: If I have min_size 2 and size
4, and because of a network issue the 4 OSDs are split into 2 and 2, is
it possible that I have write operations on both sides and therefore
have inconsistent data?

You always write to the primary, which in turn sends copies to the 3 others,
so in the 2+2 split case, only one side can talk to the primary OSD for
that pg,
so writes will just happen on one side at most.
I'm not sure that this is true, will not the side that doesn't have the primary simply elect a new one when min_size=2 and there are 2 of [failure domain] available? This is assuming that there are enough mon's also.

Even if this is the case, only half of the PGs would be available and operations will stop.



      
Thanks for clarifying!

David




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