That's exactly the steps I used to test it out. The failure I encountered was at the point of adding the StripeLVs to the MirrorVG. I don't recall the error I got but I seem to recall it being the same error as if the PV hadn't been pvcreated. Although when I went through the process again just now, without any errors... It's quite likely I mistyped or skipped a step during my first attempt... I've gone through the whole process 4 times now from raw disk to a mirrored LV without getting the error again. It looks as though this could work and isn't nearly as crazy as my initial configuration. I wonder now if anything wonky will happen if we were to lose a disk or in the original post if we lost one of the fabrics... <div>On 12/28/06, Ty! Boyack <<a href="mailto:ty@nrel.colostate.edu">ty@nrel.colostate.edu</a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Actually, I'm quite surprised that this approach mangles the lvm data. It seems that when you do a pvcreate on a block device, LVM should (and I think, does) write the lvm metadata in a region of that device, and then never let anything touch that metadata. This way, if you do a 'dd if=/dev/zeros of=<PV-DEVICE>' it blanks out the device, but the metadata is intact. So, if you do a 'pvcreate' on an LV, it should contain a second copy of the metadata, unique and independent from the first copy on the original block device. My tests on this has worked fine (although my tests have been for building two VGs that have striped volumes across the member disks, and then a VG that creates a mirrored LV of the striped volumes, so no multipathing is involved). I'm wondering if we can compare notes to see if I'm doing something that makes it look like it's working -- I don't want to be quietly destroying my lvm data and not knowing it!!! I'm doing (roughly, block devices are a bit made-up): # prepare the physical volumes pvcreate /dev/sda pvcreate /dev/sdb pvcreate /dev/sdc pvcreate /dev/sdd pvcreate /dev/sde # Create volume groups to contain uniquely striped volumes vgcreate Stripe1VG /dev/sda /dev/sdb vgcreate Stripe2VG /dev/sdc /dev/sdd # Create the striped volumes lvcreate -i 2 -n Stripe1LV -L 1G Stripe1VG lvcreate -i 2 -n Stripe2LV -L 1G Stripe2VG # Make the striped volumes into PVs pvcreate /dev/Stripe1VG/Stripe1LV pvcreate /dev/Stripe2VG/Stripe2LV # Create the volume group for mirrored volumes vgcreate MirrorVG /dev/Stripe1VG/Stripe1LV /dev/Stripe2VG/Stripe2LV /dev/sde # (Had to use three PVs to have the mirror log in place) # Create the mirrored volume lvcreate -m 1 -n Mirror1LV -L 500M MirrorVG # Filesystem, test, etc. this will be GFS eventually, but testing with ext3 for now. mke2fs -j -i16384 -v /dev/MirrorVG/Mirror1LV mkdir /mnt/mirror1lv mount /dev/MirrorVG/Mirror1LV /mnt/mirror1 Is that about your procedure as well? When does the lvm data get mangled? (Sorry if this is going off topic - but if this is solvable it might actually answer the original question...) -Ty! Matt P wrote: > This is basically the "messy" way I mentioned in my reply above. I > found if you pvcreate the LV device, you end up mangling the lvm data > (this probably comes as little surprise) and it breaks down after > that. So, I ended up using losetup and an "image file", one for/on > each fabric. Then did pvcreate on each loop device, and made a new VG > containing both PVs and created the LV with mirroring.... It > worked.... I did no performance, stability, or failure testing... -- -===========================- Ty! Boyack NREL Unix Network Manager <a href="mailto:ty@nrel.colostate.edu">ty@nrel.colostate.edu </a> (970) 491-1186 -===========================- _______________________________________________ linux-lvm mailing list <a href="mailto:linux-lvm@redhat.com">linux-lvm@redhat.com</a> <a href="https://www.redhat.com/mailman/listinfo/linux-lvm"> https://www.redhat.com/mailman/listinfo/linux-lvm</a> read the LVM HOW-TO at <a href="http://tldp.org/HOWTO/LVM-HOWTO/">http://tldp.org/HOWTO/LVM-HOWTO/</a> </blockquote></div>