Hi, I have developed a couple of resources for Linux-Cluster (CMAN +rgmanager) which try to fix some needs I see in Linux-Cluster when compared with other cluster solution (concretely, Linux-HA a.k.a. Heartbeat). I am a Linux-HA user and I think this two functionalities could be useful in Linux-Cluster.
I would like to give them (both resources) to the community to make them be into the project, and maybe after testing/quality testing or so be included into the RedHat Enterprise Linux packages of Linux-Cluster, so RedHat will give support for them and include them into the system-config-cluster tool to have a GUI that can configure this resources and handle their information. I'll give you some details of both resources: 1.- ping-group: tries to bring to Linux-Cluster the Ping Group functionality of Linux-HA. For those who don't know Ping Group, the idea is the following: its a NODE functionality (not a service or a resource) that checks IP communications with a list of given client nodes. When failed, Ping Group will move all services running in the affected node to other nodes that have proved that keep their communications right, so the service is provided to the clients even if there is a network problem that affects only a node of your cluster but the cluster itself wont realize about it. I have developed ping-group as a resource to be used into a service of your cluster, so in the resource arguments you can specify a list of clients that service should take note on. There is one thing that could be improved: ping-group will mark the service as failed even if the other nodes of the cluster would fail too due to lack of communications with the clients (for example, all clients are powered off). In this situation the service will go on migrating from one node to another according to your service failover policy and finally the service will be stopped. Maybe some ideas could be useful to improve this behaviour. 2.- lvm-cluster: tries to bring to Linux-Cluster an exclusive shared storage option, using features of LVM2. I got accustomed to this kind of volumes when working with Linux-Ha + EVMS solution (using Cluster Segment Manager plug-in). When defining a new LVM2 volume four your cluster, you can set it as cluster-disabled (the volume will behave as a local volume even if it is on shared storage) or as cluster-enabled (the LVM volume can be activated on many different cluster nodes at the same time). Of course, if the filesystem placed into the LVM volume is not a clustered filesystem (GFS2) a cluster-enabled volume allows a bad administrator mount a no-clustered filesystem (EXT3) in more than one node of the cluster which may produce filesystem corruption. This is because the LVM "open flag" of the filesystem is not propagated through all the members of the cluster, so there is no knowledge of the state of the filesystem and this situations can happen. This can be fixed with some of the options of LVM, specifically the "enable exclusively flag". This flag, when used over a cluster-enabled volume, will allow the VolumeGroup to be imported by all the nodes of the cluster but the LogicalVolumes into the VolumeGroup can only be activated by a single node. So, only one node of your cluster will have the LogicalVolume device (for example /dev/VolGrp01/LogVol01) and the problem explained above cannot happen. This is not about propagating the "open flag" through the nodes, this is about making the LogicalVolume be in only one node. I have developed lvm-cluster as a resource to be used into a service of your cluster. In the arguments you an specify the name of the VolumeGroup and the LogicalVolume to handle. So, I would like to receive the instructions to submit this two resources to the project to improve them, test them and find any bugs that could still be in the code. I have made some testing but of course they need much more to allow them be put into the main project. Sincerely yours, Rafael Micó Miranda -- Rafael Micó Miranda -- Linux-cluster mailing list Linux-cluster@redhat.com https://www.redhat.com/mailman/listinfo/linux-cluster
