On 03/08/15 22:17, Andrew Bogott wrote:
On 7/28/15 1:32 PM, Andrew Bogott wrote:
I'm running Icehouse with the 'legacy' nova-network service and a
single network node.
Everything in my cluster is running Ubuntu Trusty and ready for an
upgrade to Juno, except for my network node, which is still running
Precise.
<snip>
It turns out that I now need to do rolling restarts of my compute nodes
for an unrelated issue (see: "kvm suspend vs. the kernel") so I have a
bit more leeway with this problem. After a bit of reading I'm convinced
that while I'm messing with things it's probably a good idea to switch
to multi_host anyway. So, I propose the following steps:
1) Install nova-network on all compute nodes
2) nova-network delete (current network setting)
3) nova-network create (same network settings as in step 2 except with
multi_host on)
4) restart nova-network on all compute nodes
My supposition is that after doing that, old instances will continue to
use my old, standalone network node (as specified in their cached dhcp
settings) until they are restarted at which point they'll switch over to
using their local compute host as a router thanks to the multi_host
setting.
Can anyone confirm that this is a sensible plan, or warn me off of it?
The main danger I see is that at that after step 2, nova-compute
probably can't be safely restarted on my original compute node -- that's
definitely a bit fragile :(
Seems sane-ish. Though, the delete/create step will probably change a
network ID, which could cause badness - you might want to consider
manually updating the field in the DB instead.
Check also your DHCP timeout values - you can be lulled into a false
sense of security that things are working, then dhcp expires and all
hell breaks loose.
I'm assuming you were going to test this before touching prod, of course
:) A simple test plan would be a 3 node test cluster - two computes and
a network node. Set it up as you have your original cluster, using the
network node. Start a few VMs, then try your steps :)
Regards,
Tom
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