On Mon, Dec 04, 2017 at 11:10:16PM +0000, Riches Jr, Robert M wrote: > (This is a newbie question.) > > Having got non-LVM version 9 drbdadm working with two storage nodes and a > few no-local-storage nodes, I'm attempting to graduate to using drbdmanage > and LVM. My goal is to have two storage nodes, one pure controller node > without data storage, and a few no-local-storage compute nodes. However, I > don't understand the green box in Figure 5 in the User's Guide, labeled as a > 'Control node', 'controlvolume is a local LV', 'pure Controller', and 'nodes > without data storage'. This is the figure: > > https://docs.linbit.com/ug-src/users-guide-9.0/images/drbdmanage-venn.png > > The only LVM volume group I see mentioned in chapter 5 of the DRBD 9 UG > is the one it suggests to name 'drbdpool'. However, if the pure controller > has no data storage, how can the controlvolume be a local LV. Can someone > please enlighten a newbie on what seem to be contradictory descriptions?
There are two types of storage drbdmange can use: - the control volume (which is the cluster wide database, 2x4MB, always on thick LVM) - the storage for your actual DRBD resources (LVM/ZFS thin/thick). That makes 4 combinations: - The node has a copy of the control volume, that makes it a "control node". It can then provide storage for DRBD resources or not (control node or pure controller). A use case for a pure controller might be a "quorum node" that just has a copy of the cluster DB. Let's say you have 3 nodes, one of them is a pure controller, one of the other nodes fails then the cluster can continue as it still has 2 nodes with a copy of the control volume. - The node does not have a copy of the cluster DB and gets its cluster DB from another node via TCP. These are satellites. They can have local storage for DRBD resources or not. Regards, rck _______________________________________________ drbd-user mailing list [email protected] http://lists.linbit.com/mailman/listinfo/drbd-user
