Migration of filesystem
I will cut to the chase. I have 2 servers. Lets call them XEN and TEMP. Both machines are running ubuntu 8.04LTS server with LVM2. XEN is somehow running 32-bit where TEMP is running 64-bit. XEN is running some xen VM's using LVM as opposed to file based. Both machines are on a gigabit network with static IP's.
I need to move the running VM's off of XEN onto TEMP so I can reinstall the base OS and hypervisor as 64-bit on XEN. I know I can live migrate the XEN VM's from one server to the other by following a howto here on howtoforge. What I am having issues with is since the VM's are using LVM on XEN, how would I migrate that to TEMP so I can power down XEN and reinstall. I have done some digging and found out that I "should" be able to mount the disk in XEN onto TEMP via ISCSI, run vgmerge to merge the two volume groups into one. Then use pvmove to migrate the lv's off the original/old drive. Once I have the lv's all on TEMP I can use vgreduce and pvremove to get the drive in XEN out of the volume group.
What I am having issues with is how would I mount the disk in XEN via ISCSI to where TEMP can read them and I can migrate over? I have the target and initiator working and can mount a drive or whatever. My issue is that when I export the full physical drive, I can see the partitions (not LV's though) but cannot mount any locally on TEMP. If I export a single LV it says it contains no partitions and needs to be partitioned. I know it has a partition as it has data on it and is readable from XEN!
I know this is a one-off situation, but I think that if this is possible it would help out so many people having issues with upgrading hardware on their xen servers. This is not mandantory that I keep the VM's up and running while I do the transfer. I know that it would be so much easier if I were able to shut the machine down, copy the data over, etc. But I like a challenge and would like my sites to stay up through this, as I run my e-commerce site from one of the VM's. Any and all help/guidance is GREATLY appreciated.
I look forward to your comments and help.