> ________________________________________ > From: Clint Byrum <cl...@fewbar.com> > Sent: Wednesday, October 12, 2016 10:46 PM > To: openstack-operators > Subject: Re: [Openstack-operators] [openstack-operators][ceph][nova] How do > you handle Nova on Ceph? > > Excerpts from Adam Kijak's message of 2016-10-12 12:23:41 +0000: > > > ________________________________________ > > > From: Xav Paice <xavpa...@gmail.com> > > > Sent: Monday, October 10, 2016 8:41 PM > > > To: email@example.com > > > Subject: Re: [Openstack-operators] [openstack-operators][ceph][nova] How > > > do you handle Nova on Ceph? > > > > > > I'm really keen to hear more about those limitations. > > > > Basically it's all related to the failure domain ("blast radius") and risk > > management. > > Bigger Ceph cluster means more users. > > Are these risks well documented? Since Ceph is specifically designed > _not_ to have the kind of large blast radius that one might see with > say, a centralized SAN, I'm curious to hear what events trigger > cluster-wide blasts.
In theory yes, Ceph is desgined to be fault tolerant, but from our experience it's not always like that. I think it's not well documented, but I know this case: https://firstname.lastname@example.org/msg32804.html > > Growing the Ceph cluster temporary slows it down, so many users will be > > affected. > One might say that a Ceph cluster that can't be grown without the users > noticing is an over-subscribed Ceph cluster. My understanding is that > one is always advised to provision a certain amount of cluster capacity > for growing and replicating to replaced drives. I agree that provisioning a fixed size Cluster would solve some problems but planning the capacity is not always easy. Predicting the size and making it cost effective (empty big Ceph cluster costs a lot on the beginning) is quite difficult. Also adding a new Ceph cluster will be always more transparent to users than manipulating existing one especially when growing pool PGs) _______________________________________________ OpenStack-operators mailing list OpenStackemail@example.com http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators