Hello, I am dealing with LVM issues/thoughts with clustering for some time now... I'm detailing my architecture (which is not in production at the moment): I've got a few SAN (iSCSI-based) nodes and I've got more nodes running Xen (para-virtualization / virtual machine solution), each Xen node is connected to the SANs and can access their devices, all of them are LVM based so that I can easily manage the volumes and logical volumes. On top of each virtual machine that's running, I have a LV associated with it (the virtual machine doesn't know anything about LVM, only the physical host does, it's totally transparent for it). Also, a logical volume is never mounted twice... since 1 virtual machine = 1 lv, so I am safe on that side. All my first tests worked really fine that way....until I discovered that when I update LVM data on the SAN, the information is not refreshed on the nodes.... That's how I discovered LVM was not cluster compliant and that it was unsafe to run it that way, etc..etc... So after some researches, I found the CLVM software which is part of the whole RedHat Cluster Suite. After a few days of configuration / trial, the solution was up & ready. But this solution is not stable at all after too many nodes have joined the cluster, I have got random kernel panics, crashes, freezes, etc... which is not good for me.... and it doesn't stand my pre-production tests. Plus I have to install a lot of software, which makes sense for people that are using GFS and all the tools.... but actually I am only really using clvm.... I am looking for a MUCH MUCH simpler solution, that I could even script and write myself.... Here's my idea : -> Make LVM updates, only and simply on a master node (I am certain that no other nodes will use it) for example the SAN itself. -> The master orders all the nodes to restart the LVM software on all nodes (is there some kind of command to refresh the metadata ? vgchange ?). For more complex operations like resizing, moving, etc...kill andu umount the virtual machine first, so that it won't trash data (in case of a shrink for example) until LVM is refreshed. With my current infrastructure, issuing thoses commands would be much simpler for me than maintaining kernel-based-unstable software... But of course, I'd like the advice from experts like you please, to know, if I am not missing a big point in my idea ? or if it is not safe ? Thanks in advance, Greetings, Ugo PARSI -- An apple a day, keeps the doctor away _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
