--- On Tue, 11/23/10, Jankowski, Chris <Chris.Jankowski@xxxxxx> wrote: > From: Jankowski, Chris <Chris.Jankowski@xxxxxx> > Subject: Re: RHEL 6 cluster filesystem resource and LVM snapshots > To: "linux clustering" <linux-cluster@xxxxxxxxxx> > Received: Tuesday, November 23, 2010, 6:45 AM > Xavier, > > I do not think that I have to use CLVM with ext4 or XFS in > a cluster. > > The ext4 or XFS filesystems will be on shared (FC) storage, > but they will be presented as a filesystem resource i.e. > accessible to only one cluster at a time, as they have to > be. So, I believe that simple LVM will do and snapshots will > be available. Hi Chris first I would like to say it has been a long time since I used RHCS and the only major problems I had was with clvm, but, by your question, I think if you still foresee changes in the lvm space, you will still need clvm, even if the filesystem will be a non-cluster FS the lvm layout is independent of the filesystem used, you might want to add more volumes to a group, resize, etc, and that info is read and cached when the kernel read the device, not when mounting the filesyste, so, if the device is presented to a node of the cluster, it will read the lvm layout and filesystem properties, even if not mounted. If you change that layout in one node, the others nodes might have a wrong information that could led to a crash in case you tried to mount the fs in there. see the point of having clvm in a cluster even if using ext3/4 ? if you don't plan to use lvm for the cluster, which is possible since you are having the device from a SAN/NAS/iSCSI where you will have exactly, or almost exactly, the same features that LVM provide, why having the extra layer if you will not use it ? that is the conclusion I reached years ago when facing problems with CLVM thanks roger -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
