Migrating to another physical location

[Gumby]

Hi all,

I am looking for a few options/recommendations for the following scenario in case I have missed any options myself. I am moving about 5 hours away from where I am now. It would be really nice for me to get my proxmox VMs migrated to the new location with minimal downtime. Can anyone suggest the options for me to do this. The easy way is to just let eveyone know that the server will be down for 6-7hrs however since I have to do this move during the day on a weekday that is my least favourite option. The following are a few details about the scenario I'm facing.

* I'll need to migrate about 225GB worth of VMs
* I already have hardware running at the remote location
* 3Mbps upstream at my current location (225GB will fit within my monthly transfer limit so no extra charges there)
* Will be migrating two windows servers (one exchange server and one application server)

Thanks for any suggestions

 

[roninhockley]

put it on usb external drive for the least downtime in my opinion.

 

[Gumby]

How does this create any less down time? The time to move the external USB drive will be the same as it is to move the whole server to the new location.

If you mean, move the disk and then once the disk arrives at the new location shut down the local VM and start it at the remote location this does not work very well for an exchange server as any data written to the server between the backup point and the time the host is started at the new location will be lost. If there is something I am missing please let me know.

 

[Gumby]

To reply to my own question, I believe I have come up with a good option. I have used the patches created by aufan (and explained at http://ayufan.eu/projects/proxmox-ve-differential-backups/) so I can setup differential backups via the management interface. I'll xfer the full backup or send a disk with the full backup on it to the new location prior to doing the migration and then I'll transfer the differential backups over the internet as they are created. The following steps should ensure minimal downtime

* Get full backup to remote location either over the internet or by sending it to the new location physically
* Send daily differential backups to new location as they are created
* On day of switchover allow differential daily back up to complete, do not allow VM to re-start, send differential backup to remote location over the internet
* Restore VM at remote location
* Start VM at remote location

Can anyone see any holes in this process?

 

[roninhockley]

yea im just addressing the big data transfer initially. i can see sending the diffs over a WAN link but the 225GB i would be concerned with checksumming and all that. one other thing. how are you gonna deal with the DNS repropagation lag time to the new hosting?

 

[Gumby]

A day or so beforehand I'll set the DNS TTL to the lowest option (IIRC it is 15 minutes). Once I start the xfer I will change the the address the DNS entry itself.

 

[Norman Uittenbogaart]

If they are OpenVZ VM's it would be easy,

I would bring the USB disk to the new location.
Pause or stop the VM on the old location do a rsync with difference and resume the VM on the new location.
This will make the downtime max. 10 minutes or so ...

If they are KVM VM's, i wouldn't know
But if your dsl connection's stall's at 200GB you can start all over ...