On 14/03/18 13:33, Mark Kirkwood wrote:
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.
I probably should have shared the reasoning rather than just plumping the formula out! So here it is:
Suppose we have n hosts. The k + m fragments get spread about these n hosts,. On average, therefore (k + m)/n will be on any one of them. We want to ensure that this number is <= m (so one losing 1 host does not take out too many fragments). i.e:
(k + m)/n <= m Doing schoolboy algebra on this gets: (k + m)/m <= n Which is the stated conjecture for the minimum number of hosts. _______________________________________________ Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack Post to : openstack@lists.openstack.org Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
