[infinispan-dev] Cache migration (rolling upgrades, dump/restore, etc)

[Sebastian Laskawiec]

On Fri, May 19, 2017 at 1:18 PM Wolf Fink <wfink at redhat.com> wrote:

> +1 for Vojtech
>
> yes the client's need to moved to the new cluster in one shot current,
> that was discussed  before.
> And it makes the migration because most of the customers are not able to
> make that happen.
> So there is a small possibility of inconsistence if clients connect to the
> old server update entries until the new server already migrated it.
>
> I see two options
> 1)
> source server need to propagate active to target on update
> 2)
> with the new L4 strategy all clients are moved automatically to the
> target. So the source is not updated.
> I only see a small possibility for this to happen during switch
> - a client might still have a request to the source until other clients
> are moved to target and already accessed the key
> - a new client connects with old properties, here we need to ensure that
> the first request is redirected to the target and not update the source
>

Could you please tell me what L4 means in this context? Are you referring
to L4 routing/switching (transport level) or new Hot Rod client
intelligence?

In Kubernetes/OpenShift governing an Infinispan cluster by a Load Balancer
could do the trick. If all clients will use Service URL, once Kubernetes
kills all "old" Pods, all TCP socket connection will break and the client
will retry. This will result in massive load of error messages but the
client will eventually connect to the new cluster.


>
> On Fri, May 19, 2017 at 12:50 PM, Vojtech Juranek <vjuranek at redhat.com>
> wrote:
>
>> On středa 17. května 2017 16:56:25 CEST Tristan Tarrant wrote:
>> > 2) Need a way to "rollback" the process in case of failures during the
>> > migration: redirecting the clients back to the original cluster without
>> > data loss. This would use the above L4 strategy.
>>
>> it's not only about redirecting clients - IIRC newly created entries on
>> target
>> cluster are not propagated back to source cluster during rolling upgrade,
>> so
>> we need also somehow sync these new data back to source cluster during the
>> rollback to avoid data losses. Same applies to "cancel process" feature
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>
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-- 

SEBASTIAN ŁASKAWIEC

INFINISPAN DEVELOPER

Red Hat EMEA <https://www.redhat.com/>
<https://red.ht/sig>
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