Forum Discussion

tanislavm's avatar
tanislavm
Level 6
10 years ago

gco

hi,

i understand that a gco is a virtual(global) cluster formed from 2 vcs clusters each one in a separate site.the heartbeat between nodes from the sites goes over the wan?the gab traffic that updates all the nodes between the 2 sites,goes over this wan between sites?

business continuity
Cluster Server
  • Gaurav_S's avatar
    Gaurav_S
    10 years ago

    Hi,

    Yes, the heartbeat between two sites goes via ICMP traffic over WAN. GCO uses resource called WAC to form this heartbeat.

    If you look at GAB output, GAB will not form a membership with remote site, GAB will have local membership with local nodes. You can identify remote nodes using "hastatus -sum" command which will show status of remote site

    You can query status of heartbeat using "hahb" command ..

    https://sort.symantec.com/public/documents/vcs/6.0/solaris/productguides/html/vcs_admin/ch18s02s06.htm

     

     

    G

  • Sunil_Yadav's avatar
    Sunil_Yadav
    10 years ago

    Hi,

     

    Your understanding on GCO is right. Global Cluster Option(popularly known as GCO) is a global cluster formed from atleast 2 VCS clusters, each one in a separate site. This clusters are NOT geographically co-located(usually, separated by more than 80 kilometers).

    HB between clusters: There is ICMP based heartbeat between clusters, which goes over the WAN. You can check remote clusters HB connectivity using “hahb” command.

    E.g. In 2 cluster GCO(Pune and Mumbai), “hahb –state” executed from Pune gives connectivity between it and Mumbai cluster. 

    # haclus -state
#Cluster     Attribute                Value
Pune         ClusState                RUNNING
Mumbai       ClusState                RUNNING

# hahb -state
#HB          Attribute     Scope      Value
Icmp         State         Mumbai     ALIVE


    Message/State exchange between cluster: Wide-Area Connector(WAC) process runs on one of the node in each cluster. It is used for message/state exchange between clusters. This process listens for connection from remote clusters on port number 14155(default wac port). It is configured in ClusterService group.

    GAB: GAB maintains membership between local nodes of a cluster. It never spans across clusters. 

     

    Thanks & Regards,
    Sunil Y

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  • Gaurav_S's avatar
    Gaurav_S
    Moderator
    10 years ago

    Hi,

    Yes, the heartbeat between two sites goes via ICMP traffic over WAN. GCO uses resource called WAC to form this heartbeat.

    If you look at GAB output, GAB will not form a membership with remote site, GAB will have local membership with local nodes. You can identify remote nodes using "hastatus -sum" command which will show status of remote site

    You can query status of heartbeat using "hahb" command ..

    https://sort.symantec.com/public/documents/vcs/6.0/solaris/productguides/html/vcs_admin/ch18s02s06.htm

     

     

    G

  • Gaurav_S's avatar
    Gaurav_S
    Moderator
    10 years ago

    These posts may help you to gain further understanding ..

    https://www-secure.symantec.com/connect/forums/vcs-global-cluster-configuration

    https://www-secure.symantec.com/connect/forums/gco-configuration-between-2-nodes-cluster-and-1node-cluster

     

    G

  • Sunil_Yadav's avatar
    Sunil_Yadav
    Level 4
    10 years ago

    Hi,

     

    Your understanding on GCO is right. Global Cluster Option(popularly known as GCO) is a global cluster formed from atleast 2 VCS clusters, each one in a separate site. This clusters are NOT geographically co-located(usually, separated by more than 80 kilometers).

    HB between clusters: There is ICMP based heartbeat between clusters, which goes over the WAN. You can check remote clusters HB connectivity using “hahb” command.

    E.g. In 2 cluster GCO(Pune and Mumbai), “hahb –state” executed from Pune gives connectivity between it and Mumbai cluster. 

    # haclus -state
#Cluster     Attribute                Value
Pune         ClusState                RUNNING
Mumbai       ClusState                RUNNING

# hahb -state
#HB          Attribute     Scope      Value
Icmp         State         Mumbai     ALIVE


    Message/State exchange between cluster: Wide-Area Connector(WAC) process runs on one of the node in each cluster. It is used for message/state exchange between clusters. This process listens for connection from remote clusters on port number 14155(default wac port). It is configured in ClusterService group.

    GAB: GAB maintains membership between local nodes of a cluster. It never spans across clusters. 

     

    Thanks & Regards,
    Sunil Y

  • mikebounds's avatar
    mikebounds
    Level 6
    10 years ago

    Just to clarify, LLt/GAB is very "chatty" so will communicate all state and config changes down to resource level between nodes in a local cluster.  For GCO, there is no GAB between sites and instead there is a "wac" (wide area connector) resource in the ClusterService group which communicates with the wac resource in the other globally connected clusters (as Sunil says above).  The wac resource is a lot less chatty and only communicates state of group and cluster (not resources).

    The wac resource communicates on the address specified by the "ClusterAddress" cluster attribute and you also have a global heartbeat which is normally the same IP, but it can be a different network if you have one and the heartbeat just transmits AYA (are you alive).

    Mike