Share mount between 2 service groups
Hello Guys,
I am in the process of setting up 2 service group and runs independently, but one of the mount needs to be shared between both service groups.
How can I do that?
You can have three service groups, one service group that provides the mount (diskgroup, volume, mount), and then two more service groups for the application (NIC, IP, APP) that depend on the mount service group.
You cannot share a diskgroup between Service Groups.
All of the hardware and software components needed for High Availability of an Application need to be contained in a Service Group.
If one dg was part of more than one SG, then a fault in one of the SGs would cause the other SG to go offline as well.
As per Riaan's excellent post, you can read up about Service Group dependencies where one SG must be online before another SG(s) can come online.
If you want "2 service group and runs independently" then this implies to me you want each service group to failover independently. This will not work with diskgroup, volume and mount resources, so in Riaans solution the service group dependency would need to be online local which means all 3 service groups would need to failover together which sort of defeats the point of having them in separate groups so all this really does is make it easier to offline each component (i.e you can offline group as oppose to offline individual resources in a group).
So if you want independence then you will need to use SFCFS. A SFCFS HA licence costs the same as SF HA when bought new and only costs more if you upgrade SFCFS HA from SFHA. With SFCFS you would have a parallel group with CVMVolDg and CFSMount resources which would activate your diskgroup and mount the filesystems on both nodes at the same time. You can then have 2 separate service groups which can be online local dependent on this parallel group and these 2 groups would be independent and could run on the same or different systems and failover independently of each other.
You could also use FSS - see https://www-secure.symantec.com/connect/forums/sfha-solutions-61-linux-share-local-storage-across-network-using-flexible-storage-sharing which essenially shares local storage between servers using the network via the VCS heartbeats. The sharing is done at disk level so that a "vxdisk list" would show local disks from the other node in the cluster.
Mike
