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Cool idea, and please let us know if you implement it and the result works. But I feel compelled to also point you to vmware's vmotion product :-) On 7/12/08, Kent Borg <[hidden email]> wrote: > Anyone here have experience with ATA over Ethernet ("aoe")? > > To be specific, here is my idea: I want to do more of that trendy > "server consolidation" but not have all my eggs in one basket. So I > imagine having two identical physical machines, each set up to match the > other. Normally I run all the VMs on one machine. Worrying about disks > dying I put each VM on a pair of software raid 1 disks in that box. But > how do I quickly switch to the other physical machine? > > Here is where I get clever (and ask for advice): On the other machine I > do the exact same thing. VM on a pair of software raid 1 partitions. > But how to sync them up? > > First, shut down the spare copy. Only run one copy of the VM at a time. > > Second, shutdown the md device for that spare copy. > > Third, export the two physical partions via ATA over ethernet. (Be an > aoe target.) > > Fourth, on the primary machine, import the two partitions via ATA over > ethernet. (Be an aoe initiator.) > > Fifth, on the primary machine, add the two partitions to the raid 1 md > device. Wait for the data to copy, but still keep the VM running and > serving whatever good stuff it does. > > > I haven't researched it much, but if I have dedicated gigabit ethernet > )or faster) and a crossover cable, and do a large MTU hack on those two > NICs, maybe the ATA over ethernet could mostly keep up with the local > disks? Or maybe not... > > Next obvious idea would be to not ship both partitions over the ethernet > cable separately, but to put them together into a raid 1 pair first and > instead ship the md device over the cable. > > But there is something else I would like to do: run the VM on one > physical machine, shut it down, reverse the ATA over ethernet setup, > boot the VM on the other physical machine, and have the various md > components all happy and in synch with no replication necessary. Doing > a flat collection of 4 distinct physical partitions would probably > work. But if I did nested and rehanging the tree, a complete > replication would have to happen unless I did some hacking. > > Example. > > case 1: > - yin's sda1 > - yin's sdb1 > - yang's aoe, which is > - yang's sda1 > - yang's sdb1 > > case 2: > - yang's sda1 > - yang's sdb1 > - yin's aoe, which is > - yin's sda1 > - yin's sdb2 > > Is there a way to hack md internals to make the two cases boot back and > forth and keep the md in synch both ways? > > > Practical consession: maybe just running in this aoe mode while messing > with configurations and migrating VMs, and just run local raid 1 when > things are stable. > > > Comments? > > > Thanks, > > -kb > > -- > This message has been scanned for viruses and > dangerous content by MailScanner, and is > believed to be clean. > > _______________________________________________ > Discuss mailing list > [hidden email] > http://lists.blu.org/mailman/listinfo/discuss >
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