Hello, I am trying to find out a best practice for a specific scenario. First of all I would like to know what is the proper way to set up multipath, who should care about it the host or the guest. Right now I have a setup where I have one multipath which sets my host to boot from FC SAN. I have another multipathed LUN in the host which is essentially a dm which I attached to a guest, however through virtio. I added the devices through virsh with pool type of "mpath" and path through /dev/mapper/. So here is my first question: with such a setup the multipath and eventual fail-over is taken care by the host OS, right, the guest will not notice is I suppose? But what about migration. What if I decide to migrate the guest to another host. How would that work out? WIth shared directory it is easy, you just have the images in it, but what about such a setup. I can always add the aforementioned LUN, where the guest resides to another Storage Group on the SAN where the new host has access and I can make sure that the mpath device name is persistent across all hosts, but is that the right approach. Here is another question that is bugging me. I have FC HBA-s on all hosts and I would like to make a HBA visible through my guest. I stumbled upon a bug that is documented in redhat's bugzilla that attempted creation of NPIV on pci_0000_blah_blah instead on the scsi_hostX device, but I fixed that easily in the xml and although virsh doesn't seem to think I completed the nodedev-create NPIV_for_my_FC.xml the device is seen as a child in nodedev-list and what is more important the WWN are seen on the SAN switch. So this seems to be working OK, however I don't know how to attach this new shiny device that I created to a guest. Could someone give me a hint? What is the proper way to attach this new devices to a guest OS and do that persistently. Do I do that with virsh's attach-device and if so what is the proper XML format? Should I dump the XML for the newly created NPIV nodedev and try to attach that? And again with multipathing. What if I decided to create NPIV on my two FC cards in every host, then do the zoning and attach those newly created NPIV nodes to the guests? Will that produce the same effect that such a multipath does on the host? It doesn't really matter if I would use it for root drive or a shared gfs2 storage between guests, I just want to know is this possible and is it the right thing to do, or should I stick to setup in my previous paragraph? And last question: what about migration with such NPIV FC devices. I can move a guest around, but will that move my NPIV FC with it's WWN so that I can continue using my zoning (I think I just realized that this might be impossible because I'm migrating the guest, not the entire setup of libvirt, but probably I'm wrong and I'm not aware of a proper method to do it correctly?). Probably those questions are easy to answer, but please bare with me, I'm playing with libvirt in an enterprise setup only for the last couple of days and I would really like to make it right and kick some VMware ass. By the way, all my hosts are Fedora 14, with kernel 2.6.37 (rebuild of the one for Fedora 15 from koji, because there was a small glitch with Qlogic's driver in the stock 2.6.35). Most of my guests will be SL6,CentOS5/6(when it arrives) and a couple of windows XP guests (but I'm not really concerned with that). Thanks for the support in advance P.S. please keep me in CC, as I'm not on the list. Thank you