Beuh ... I have other questions: - why not use LVM, and stick with direct disk access ? - what are the cost of LVM (performance, latency etc) ? Answers: - unify setup, support for crypto & more - none Tldr: that technical choice is fine, nothing to argue about. On 06/08/2018 07:15 AM, Marc Roos wrote: > > I am getting the impression that not everyone understands the subject > that has been raised here. > > Why do osd's need to be via lvm, and why not stick with direct disk > access as it is now? > > - Bluestore is created to cut out some fs overhead, > - everywhere 10Gb is recommended because of better latency. (I even > posted here something to make ceph better performing with 1Gb eth, > disregarded because it would add complexity, fine, I can understand) > > And then because of some start-up/automation issues (because that is the > only thing being mentioned here for now), lets add the lvm > tier? Introducing a layer that is constantly there and adds some > overhead (maybe not that much) for every read and write operation? > > > > > > -----Original Message----- > From: Nick Fisk [mailto:nick@xxxxxxxxxx] > Sent: vrijdag 8 juni 2018 12:14 > To: 'Konstantin Shalygin'; ceph-users@xxxxxxxxxxxxxx > Subject: Re: Why the change from ceph-disk to ceph-volume > and lvm? (and just not stick with direct disk access) > > http://docs.ceph.com/docs/master/ceph-volume/simple/ > > ? > > > > From: ceph-users <ceph-users-bounces@xxxxxxxxxxxxxx> On Behalf Of > Konstantin Shalygin > Sent: 08 June 2018 11:11 > To: ceph-users@xxxxxxxxxxxxxx > Subject: Re: Why the change from ceph-disk to ceph-volume > and lvm? (and just not stick with direct disk access) > > > > What is the reasoning behind switching to lvm? Does it make sense > to go > through (yet) another layer to access the disk? Why creating this > dependency and added complexity? It is fine as it is, or not? > > In fact, the question is why one tool is replaced by another without > saving functionality. > Why lvm, why not bcache? > > It seems to me that in the heads dev team someone has pushed the idea > that lvm solves all problems. > But this is also added the overhead, and since this is a kernel module > with a update we can get a performance drop, changes in module settings, > etc. > I understand that for Red Hat Storage this is a solution, but for a > community with different distributions and hardware this may be > superfluous. > I would like to get back possibility of preparing osd's with direct > access was restored, and let it not be the default. > Also this will save configurations for ceph-ansible. Actually I was > don't know what is create my osd's ceph-disk/ceph-volume or whatever > before this deprecation. > > > > > > k > > > > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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