Hi all, Thanks for the replies. The main reason why I was looking for the thin/thick provisioning setting is that I want to be sure that provisioned space should not exceed the cluster capacity. With thin provisioning there is a risk that more space is provisioned than the cluster capacity. When you monitor closely the real usage, this should not be a problem; but from experience when there is no hard limit, overprovisioning will happen at some point. Sinan > I can only speak for some environments, but sometimes, you would want to > make sure that a cluster cannot fill up until you can add more capacity. > > Some organizations are unable to purchase new capacity rapidly and making > sure you cannot exceed your current capacity, then you can't run into > problems. > > It may also come from an understanding that thick provisioning will > provide > more performance initially like virtual machines environment. > > Having said all of this, isn't there a way to make sure the cluster can > accommodate the size of all RBD images that are created. And ensure they > have the space available? Some service availability might depend on making > sure the storage can provide the necessary capacity. > > I'm assuming that this is all from an understanding that it is more costly > to run such type of environments, however, you can also guarantee that you > will never fill up unexpectedly your cluster. > > Sam > > On Oct 18, 2017 02:20, "Wido den Hollander" <wido@xxxxxxxx> wrote: > > >> Op 17 oktober 2017 om 19:38 schreef Jason Dillaman >> <jdillama@xxxxxxxxxx>: >> >> >> There is no existing option to thick provision images within RBD. When >> an image is created or cloned, the only actions that occur are some >> small metadata updates to describe the image. This allows image >> creation to be a quick, constant time operation regardless of the >> image size. To thick provision the entire image would require writing >> data to the entire image and ensuring discard support is disabled to >> prevent the OS from releasing space back (and thus re-sparsifying the >> image). >> > > Indeed. It makes me wonder why anybody would want it. It will: > > - Impact recovery performance > - Impact scrubbing performance > - Utilize more space then needed > > Why would you want to do this Sinan? > > Wido > >> On Mon, Oct 16, 2017 at 10:49 AM, <sinan@xxxxxxxx> wrote: >> > Hi, >> > >> > I have deployed a Ceph cluster (Jewel). By default all block devices > that >> > are created are thin provisioned. >> > >> > Is it possible to change this setting? I would like to have that all >> > created block devices are thick provisioned. >> > >> > In front of the Ceph cluster, I am running Openstack. >> > >> > Thanks! >> > >> > Sinan >> > >> > _______________________________________________ >> > ceph-users mailing list >> > ceph-users@xxxxxxxxxxxxxx >> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> >> >> -- >> Jason >> _______________________________________________ >> 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 > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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