Thanks Christian. Replies inline. On Sep 6, 2014, at 8:04 AM, Christian Balzer <chibi at gol.com> wrote: > > Hello, > > On Fri, 05 Sep 2014 15:31:01 -0700 JIten Shah wrote: > >> Hello Cephers, >> >> We created a ceph cluster with 100 OSD, 5 MON and 1 MSD and most of the >> stuff seems to be working fine but we are seeing some degrading on the >> osd's due to lack of space on the osd's. > > Please elaborate on that degradation. The degradation happened on few OSD's because it got quickly filled up. They were not of the same size as the other OSD's. Now I want to remove these OSD's and readd them with correct size to match the others. > >> Is there a way to resize the >> OSD without bringing the cluster down? >> > > Define both "resize" and "cluster down". Basically I want to remove the OSD's with incorrect size and readd them with the size matching the other OSD's. > > As in, resizing how? > Are your current OSDs on disks/LVMs that are not fully used and thus could > be grown? > What is the size of your current OSDs? The size of current OSD's is 20GB and we do have more unused space on the disk that we can make the LVM bigger and increase the size of the OSD's. I agree that we need to have all the disks of same size and I am working towards that.Thanks. > > The normal way of growing a cluster is to add more OSDs. > Preferably of the same size and same performance disks. > This will not only simplify things immensely but also make them a lot more > predictable. > This of course depends on your use case and usage patterns, but often when > running out of space you're also running out of other resources like CPU, > memory or IOPS of the disks involved. So adding more instead of growing > them is most likely the way forward. > > If you were to replace actual disks with larger ones, take them (the OSDs) > out one at a time and re-add it. If you're using ceph-deploy, it will use > the disk size as basic weight, if you're doing things manually make sure > to specify that size/weight accordingly. > Again, you do want to do this for all disks to keep things uniform. > > If your cluster (pools really) are set to a replica size of at least 2 > (risky!) or 3 (as per Firefly default), taking a single OSD out would of > course never bring the cluster down. > However taking an OSD out and/or adding a new one will cause data movement > that might impact your cluster's performance. > We have a current replica size of 2 with 100 OSD's. How many can I loose without affecting the performance? I understand the impact of data movement. --Jiten > Regards, > > Christian > -- > Christian Balzer Network/Systems Engineer > chibi at gol.com Global OnLine Japan/Fusion Communications > http://www.gol.com/
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