Re: CRUSH map help

[Gregory Farnum <gfarnum@xxxxxxxxxx>]

On Thu, May 12, 2016 at 2:54 PM, Stephen Mercier <stephen.mercier@xxxxxxxxxxxx> wrote:

Thank you very much for the thorough explanation. What you described was one of the ways I was interpreting this.

Now, out of curiosity, if I did:

rule replicated_rack {

ruleset 0

type replicated

min_size 1

max_size 10

step take default

        step choose firstn 2 type rack

step chooseleaf firstn 2 type host

step emit

}

Would that choose the 2 racks, and then 2 osds from each host, making sure that in a 3x replication scenario, I would ensure that all 3 reps would be on different servers as well? Just want to make sure I'm following the logic correctly before I pull any triggers.

Yep!

 

On Thu, May 12, 2016 at 2:57 PM, Stephen Mercier <stephen.mercier@xxxxxxxxxxxx> wrote:

Also, when you say new enough for the overselection hack, how new are we talking?!?!

Not very. I'm honestly not sure and you're best off experimenting — all the current userspace stuff is fine; there might still be a kernel client in LTS releases which won't be happy with it.

-Greg

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