Libro sobre Proxmox maestria
MDS
MDS stores Meta information for Ceph FS. Ceph Block and Object Storage do not use MDS. So in a cluster, if Block and Object are the only types being used, it is not necessary to set up an MDS server. Like Monitors, MDS needs to be set up on a different machine to achieve high performance. As of Proxmox Version 3.2, MDS cannot be managed or created from the Proxmox GUI.
Ceph FS is not fully standardized yet and is still in the development phase. It should not be used to store mission critical data. It is mostly stable, but unforeseen bugs may still cause major issues such as data loss. Note that there have not been many reports of mass data loss due to unstable Ceph FS. Two of the virtual machines used to write this book have been running for more than 11 months without any issue.
There should be two MDS nodes in a cluster to provide redundancy because the loss of an MDS node will cause the loss of data on Ceph FS and will render it inaccessible. Two MDS nodes will act as active+passive when one node failure is taken over by another node and vice versa. To learn about MDS and Ceph FS, visit http://ceph. com/docs/master/cephfs/.
The main function of Placement Group (PG) is to combine several objects into a group and then map the group to several OSDs. A per-group mechanism is much more efficient than a per-object mechanism since the former uses fewer resources. When data is retrieved, it is far more efficient to call a group than an individual object in a group. The following diagram shows how PGs are related to OSD: