I have an iSCSI server (using LIO) which provides one LUN. Two client machines each connect this same LUN. From the client's perspective, let's say it shows up as device /dev/sda. I have then in one client created a partition /dev/sda1 with type 8e (LVM). The partition immediately shows up in the other client.
After that, I have created a physical LVM volume (pvcreate /dev/sda1) and a volume group (vgcreate shared /dev/sda1). Note that I have not enabled cluster mode for this volume group. Again, both the physical volume and the volume group are immediately visible to the other client.
When I create in one client a logical volume in this volume group, it is visible to the other client, but it is unavailable. This works in both directions, i.e. I can create a logical volume in one client or the other, and it is always visible, but unavailable to the other client.
So far, everything seems to work fine. Now my question is: Is this setup sufficient or do I need cLVM? I have tried to install cLVM, but had some problems, because I do not have (and probably do not need?) a cluster manager.
Could anybode explain when cLVM is needed in general and if it is necessary for me?