nova team mailing list archive

[Michael Gundlach <michael.gundlach@xxxxxxxxxxxxx>]

On Fri, Oct 8, 2010 at 5:03 AM, Soren Hansen <soren@xxxxxxxxxx> wrote:

> > We want to support 1 million instances, right?  Which is 1/4000 the
> > keyspace, so we have something like a 1 in 4000 chance of a
> > collision once we hit a million instances.
>
> Mm... Not exactly. 1/4000 is the chance of collision for the last one,
> assuming an even distribution.
>
> You reach a 1/4000 chance of having had *a* collision before you
> even start 150 instances. After a million instances, that figure grows
> to 99.99999999999999999999999999999999999999999999999999% or
> thereabouts. We're in 99% territory after a measly 200,000 instances.
>

Thank you!  Just the statistics that I needed :)

pvo already pointed out that I'm an idiot, and we're not trying to support
1MM virtual instances, we're targeting 1MM physical hosts.  So next week
I'll be making this 64 bits for Austin, and as Ewan said, next month we can
discuss what we want to do for Bexar.

Michael


Confidentiality Notice: This e-mail message (including any attached or
embedded documents) is intended for the exclusive and confidential use of the
individual or entity to which this message is addressed, and unless otherwise
expressly indicated, is confidential and privileged information of Rackspace.
Any dissemination, distribution or copying of the enclosed material is prohibited.
If you receive this transmission in error, please notify us immediately by e-mail
at abuse@xxxxxxxxxxxxx, and delete the original message.
Your cooperation is appreciated.