Hi, Maybe others had your mail going into junk as well, but that is why at least I did not see it.
To your question, which I’m not sure I understand completely. In Ceph you have three distinct types of services, Mon, Monitors MDS, Metadata Servers OSD, Object Storage Devices And some other concepts PG, placement group Object Pool So a Pool contains PGs that contains Objects, in that order. Monitors keeps track of pools and PGs, and the objects are kept on the OSD. In case you’re running CephFS, the Ceph File System, you also have files, which the MDS keeps track of. So yes, you don’t need the MDS if you just keep track of block storage and object storage. (i.e. images for KVM) So the Mon keeps track of the metadata for the Pool and PG and the MDS keep track of all the files, hence the MDS should have at least 10x the memory of what the Mon have. I’m no Ceph expert, especially not on CephFS, but this is my picture of it :) Maybe the architecture docs could help you out? http://docs.ceph.com/docs/master/architecture/#cluster-map <http://docs.ceph.com/docs/master/architecture/#cluster-map> Hope that resolves your question. Cheers, Josef > On 06 Apr 2015, at 18:51, pragya jain <prag_2...@yahoo.co.in> wrote: > > Please somebody reply my queries. > > Thank yuo > > ----- > Regards > Pragya Jain > Department of Computer Science > University of Delhi > Delhi, India > > > > On Saturday, 4 April 2015 3:24 PM, pragya jain <prag_2...@yahoo.co.in> wrote: > > > hello all! > > As the documentation said "One of the unique features of Ceph is that it > decouples data and metadata". > for applying the mechanism of decoupling, Ceph uses Metadata Server (MDS) > cluster. > MDS cluster manages metadata operations, like open or rename a file > > On the other hand, Ceph implementation for object storage as a service and > block storage as a service does not require MDS implementation. > > My question is: > In case of object storage and block storage, how does Ceph manage the > metadata? > > Please help me to understand this concept more clearly. > > Thank you > > ----- > Regards > Pragya Jain > Department of Computer Science > University of Delhi > Delhi, India > > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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