On Sun, Jul 31, 2016 at 12:21 PM, Adrian <[email protected]> wrote: > What is the best way to mirror an Ubuntu server that runs several VMs > to an identical hardware configuration for the purpose of having a > stand-by warm swap server.
Obviously there is no single approach that is "the best way". Instead, what you will end up with will be lots of different techniques with differing costs/complexities, offering different benefits :-) Many of them will say "if you were doing things differently from the beginning ..." - consider these, the cost of reworking your environment to fit the answer might be better than trying to retrofit availability into your current environment ... But, I guess it's reasonable to look for the approach that has the least change from your current working practices, so you don't have to change too much at one go and therefore lose understanding of how the system actually works. Step Zero: Backups of everything are essential - remember that "a backup is not a backup unless you can restore, so test restore every time you backup". If you can restore from backup quickly enough, you might already have your near-real-time spare. Question One: How will you switch between the two? What IP addresses will they have, when? If you change the IP of one machine to the "primary" address, will your local network switch realise you've changed MAC address? Or will you change that too? (If you do change IP address, how will you know that you're logged in to the correct server - especially important while they are both working). Will you change the primary status using the local firewall/router? If your machines are on the same LAN, you might approach the problem by making the two machines identical in real-time, perhaps by using disk-level clustering; DRDB is a great approach for this, very mature. If all the user data (i.e. the VMs, etc) are on the shared volume, either machine will get the same view. If the two machines have the same OS-level configuration, either can do the job of running the VM - but you're going to need to make sure that they don't both attempt to do so at the same time. That's a start - does that help? -jim _______________________________________________ Linux-users mailing list [email protected] http://lists.canterbury.ac.nz/mailman/listinfo/linux-users
