Oops! <blush/> On Tue, Oct 5, 2010 at 5:52 PM, Paul Voccio <[email protected]>wrote:
> Michael, > > I think we want to support 1mm host machines with the system. The limit of > 1mm VMs might be a bit, umm, limiting. > > Pvo > > > > On 10/5/10 1:39 PM, "Michael Gundlach" <[email protected]> > wrote: > > On Tue, Oct 5, 2010 at 2:31 PM, Ewan Mellor <[email protected]> > wrote: > > Thanks Michael. It would be great to see this in some doccomments in the > code somewhere. > > > Yeah, I agree -- I first touched this code to rename ec2_id to internal_id, > and it's been a bit of a pain because there's a dearth of comments (and some > ambiguous naming, like "instance_id" referring to id in some places and to > ec2_id in other places.) I plan to clean this code up as one of my post-FF > tasks. > > > I agree with Jay's comments elsewhere in this thread -- it seems a better > idea to use a UUID for your internal_id, rather than a long int. That way, > the ID is an extra 64 bits longer, so you can generate them randomly on > independent nodes without worrying about collisions. > > > I think we discussed this in IRC -- 128 bits turns into a 26 byte EC2 ID vs > 14 for a 64 bit int, and someone (Soren?) had a strong negative preference. > > Actually, I just checked in code only using a 32 bit integer, and I'd like > some convincing that this isn't sufficient for the foreseeable future. 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. I know I'm not doing the statistics properly, since the > proper question is "what is the chance of at least one collision when > successively generating one million random 32-bit integers?", but it feels > like we can punt on larger values at least until Bexar. > > Thoughts? > > 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 [email protected], and delete the original message. > Your cooperation is appreciated. > >
_______________________________________________ Mailing list: https://launchpad.net/~nova Post to : [email protected] Unsubscribe : https://launchpad.net/~nova More help : https://help.launchpad.net/ListHelp
