On Monday 01 June 2009 21:17:30 Rafael Micó Miranda wrote: > 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: [...] > > 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. [...] This looks very useful. We are using a shared storage with CLVM, and a non- clustered FS. I always fear mounting the same FS on different nodes. I have always hoped this feature could exist the LVM layer. It would be great to see this incorporated in CLVM. -- Xavier Montagutelli Tel : +33 (0)5 55 45 77 20 Service Commun Informatique Fax : +33 (0)5 55 45 75 95 Universite de Limoges 123, avenue Albert Thomas 87060 Limoges cedex -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
