Forum Discussion

tanislavm's avatar
tanislavm
Level 6
11 years ago

shared and non shared disk group in cluster

Hi, I wish to verify the following. On VCS with CFS we must add logical volumes only on master node.On VCS without CFS we could add resources from any cluser node.Right? the master node is the node where we have created for the first time the disk group and the resources within it? vxdctl -c mode on VCS without CFS will give no output.Right?
business continuity
Cluster Server
Solaris
  • Gaurav_S's avatar
    Gaurav_S
    11 years ago

    Ok..  first thing to understand, in a cluster without CFS, there is nothing called master/slave. In a normal VCS setup (without CFS), if one node has imported the diskgroup, we can call it as primary node because resources are running there but its not called master node.

    I thought that on VCS without CFS we could add logical volume only on the node that has imported the disk group who contains the logical volumes.Right?

    --> right, where diskgroup is imported, that is where diskgroup/volume level functions can be performed.


    Here on VCS without CFS we have SCSI permanent reservation so the disk group will be seen only by the node who has written the signature on that disk group.The other nodes in cluster do not see that disk group.right?

    --> well other nodes in VCS will still see the diskgroup in deported state but again, whether fencing is in use or not, which ever node diskgroup is imported, you can make changes on that node


    If I perform VCS things on VCS with CFS I am able to perform VCS things from any node.Right?

    --> right

     

    G

  • Gaurav_S's avatar
    Gaurav_S
    Moderator
    11 years ago

    Hi,

    On VCS with CFS we must add logical volumes only on master node

    --> Yes, all volume manager layer functions will go from master node only. Any VCS configuration modfication can be done from any node in VCS.

    On VCS without CFS we could add resources from any cluser node.Right?

    ---> This is tru for VCS, you can add resources from any node, doesn't matter if you are on master or slave node. As explained, if you are doing VCS level operations, you can do it from any node however if anything is at volume manager layer (creating a new volume etc) needs to be done from master node.

    The master node is the node where we have created for the first time the disk group and the resources within it?

    --> If you have already installed the SFCFS stack, well you would already have a master node in the CVM/CFS cluster. It is quite possible that you created resources on some node which was master earlier but later on another node was given role of master. In SFCFS cluster, if master node fails, the master rights are passed on to any other available node in cluster.

    vxdctl -c mode on VCS without CFS will give no output.Right?

    Right ..you may get something like "cluster inactive"

     

    G

     

     

     

     

  • tanislavm's avatar
    tanislavm
    Level 6
    11 years ago
    Hi, If on VCS without CFS the output of vxdctl -c mode is like "cluster inactive",then in this scenario there are an master node and slave node? So on both cases VCS with CFS and VCS without CFS when we add logical volumes in disk group,the operation is done on master node.rght? tnx a lot, marius
  • Gaurav_S's avatar
    Gaurav_S
    Moderator
    11 years ago

    If on VCS without CFS the output of vxdctl -c mode is like "cluster inactive",then in this scenario there are an master node and slave node?

    ---> vxdctl -c mode if a CFS cluster is running would return the output indicating which is a master node. for e.g

    # vxdctl -c mode
    mode: enabled: cluster active - MASTER
    master: system02

    If the CFS cluster is not working, that's where you should get "cluster inactive". I don't remember exactly but in a normal VCS installation if you run "vxdctl -c mode", you should either get no output OR cluster inactive. for e.g

    The following output is displayed on a node that is not a member of the cluster:
    # vxdctl -c mode
    mode: enabled: cluster inactive

     

    So on both cases VCS with CFS and VCS without CFS when we add logical volumes in disk group,the operation is done on master node.rght?

    ---> master /slave concept is only there for SFCFS, so when you are adding logical volumes in a diskgroup in SFCFS setup, you need to execute commands on master node, however in a normal VCS setup (without CFS), you can do diskgroup/volume level functions from any node

     

    G

  • tanislavm's avatar
    tanislavm
    Level 6
    11 years ago
    hi, I thought that on VCS without CFS we could add logical volume only on the node that has imported the disk group who contains the logical volumes.Right? Here on VCS without CFS we have SCSI permanent reservation so the disk group will be seen only by the node who has written the signature on that disk group.The other nodes in cluster do not see that disk group.right? If I perform VCS things on VCS with CFS I am able to perform VCS things from any node.Right? tnx, marius
  • Gaurav_S's avatar
    Gaurav_S
    Moderator
    11 years ago

    Ok..  first thing to understand, in a cluster without CFS, there is nothing called master/slave. In a normal VCS setup (without CFS), if one node has imported the diskgroup, we can call it as primary node because resources are running there but its not called master node.

    I thought that on VCS without CFS we could add logical volume only on the node that has imported the disk group who contains the logical volumes.Right?

    --> right, where diskgroup is imported, that is where diskgroup/volume level functions can be performed.


    Here on VCS without CFS we have SCSI permanent reservation so the disk group will be seen only by the node who has written the signature on that disk group.The other nodes in cluster do not see that disk group.right?

    --> well other nodes in VCS will still see the diskgroup in deported state but again, whether fencing is in use or not, which ever node diskgroup is imported, you can make changes on that node


    If I perform VCS things on VCS with CFS I am able to perform VCS things from any node.Right?

    --> right

     

    G