Open Stack

On 14/03/18 11:47, Clay Gerrard wrote:

>
>
> On Tue, Mar 13, 2018 at 3:05 PM, Mark Kirkwood 
> <mark.kirkwood at catalyst.net.nz <mailto:mark.kirkwood at catalyst.net.nz>> 
> wrote:
>
>     To me this suggests that a certain minimum number of *hosts* per
>     region is needed for a given EC policy to be durable in the advent
>     of host outage (or destruction). Is this correct - or have a
>     flubbed the calculations?
>
>
> Looks correct to me.  Ideally you'd have more nodes per region than 
> k+m; otherwise a reboot would mean WAN traffic - or if that's not 
> possible - temporary unavailability.
>
>
Awesome thanks!

Doing a bit more playing about leads me to think that for a *single 
region* EC policy we can get a tighter lower bound on the number of 
hosts: I'm calculating it as (k+m)/m. So in the case I was playing with 
before (k=8, m=2), then I need 5 hosts in my region. While testing does 
seem to support this, does it sound reasonable?

Cheers
Mark