Greetings. Red Hat says they only support fresh installs of the OS as a way to move from one backend Storage SAN to another. This seems strange since I have been able to migrate boot LUNs for numerous Unix based systems over the years.
I took a RHEL6 server that was due to be rebuilt with RHEL 7 (it had no issues, application updates require RHEL7 in the future) we thought we would test migrating it from old SAN to new SAN since we have a bunch of server clusters that are in production with no option to rebuild them. The server boots from san otherwise we would have no issue. I've got all the data migrated including cloning the OS onto a new LUN. I ran all the steps I could find that would migrate the boot/grub and all the stuff outside of systemvg. What I am left with is it boots to a grub prompt. If I put in all the same options and paths that I saves in the grub config and wrote to disk it will boot the OS just fine and everything works. I feel like I missed some small step that is eluding me and with no support from the OS vendor I am reaching out to the list to see if I can resolve this and move the rest of the servers I need to without having to take down production clusters to re-load operating systems. Here is the grub boot strings that work to bring the system up from the grub prompt. root (hd0,0) kernel /vmlinuz-2.6.32-754.28.1.el6.x86_64 ro root=/dev/mapper/systemvg-sysroot rd_NO_LUKS rd_LVM_LV=systemvg/sysroot rd_LVM_LV=systemvg/swap initrd /initramfs-2.6.32-754.28.1.el6.x86_64.img Here is how I cloned the OS disk to a LUN provided by the new SAN (devices are generic because I was documenting how to do it for the other migrations) Update /etc/lvm.conf to add a filter for mpath. Add the following "a/dev/mapper/mpath.*/", to the filter line (watch spacing) including the quotation marks. sfdisk -d /dev/source_hdisk | sfdisk --force /dev/target_hdisk pvcreate /dev/mpath_device_partition (ex /dev/mapper/mpathbp2 this was the partition for systemvg) vgextend systemvg /dev/mpath_device_partition (ex /dev/mapper/mpathbp2) pvmove /dev/source_lvm_partition (ex /dev/emcpowerca2) vgreduce /dev/source_lvm_partition (ex /dev/emcpowerca2) pvremove /dev/source_lvm_partition (ex /dev/emcpowerca2) clone boot umount /boot/ dd if=/dev/source_boot_partition (ex /dev/emcpowerca1) of=/dev/target_boot_partition (ex /dev/mapper/mpathbp1) bs=512 conv=noerror,sync mount /boot copy boot sector dd if=/dev/source_disk (ex /dev/emcpowerca) of=/dev/target_disk (ex /dev/mapper/mpathb) bs=1 count=512 update grub device map (make sure this is mounting the mpath location) vi /boot/grub/device.map update line for the target disk to have the target disk (ex /dev/mapper/mpathb) install grub in new disk grub-install /dev/target_disk (ex /dev/mapper/mpathb) sync changes sync This email and its attachments may contain privileged and confidential information and/or protected health information (PHI) intended solely for the use of Netsmart Technologies and the recipient(s) named above. If you are not the recipient, or the employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any review, dissemination, distribution, printing or copying of this email message and/or any attachments is strictly prohibited. If you have received this transmission in error, please email [email protected] immediately and permanently delete this email and any attachments.
