[NEW] Support for Active/Active replication about valkey

[cjabrantes]

Just to add that besides Redis Enterprise, also keydb (open source redis drop-in) is supporting it and the configuration is quite trivial:
--multi-master yes
--active-replica yes
--replicaof IP PORT

@madolson:
Dont know if helps or even if your question was in this direction, but from https://docs.keydb.dev/docs/active-rep:
Split Brain
KeyDB can handle split brain scenarios where the connection between masters is severed, but writes continue to be made. Each write is timestamped and when the connection is restored each master will share their new data. The newest write will win. This prevents stale data from overwriting new data written after the connection was severed.

IMHO (i may be wrong) I think this is a great feature as it is a simple and cheap way to get HA without manual intervention (as all nodes accept writes, no need of election) and without the complexity (resources, elections) of cluster/sentinel setups.

I would really like to use Valkey, but "unfortunately" i need this feature.

[cjabrantes]

@madolson,
Sadly i dont know how it behaves.

[madolson]

Can you add some additional information about what types of workloads you are trying to support. Active/Active replication is a hard problem with a lot of tradeoffs. It would be helpful to have more information about your specific usecase to inform those tradeoffs.

[Amitgb14]

It might be this possible only on Proxy level. It make more complex if it start support in core Valkey code.

[btzq]

Can you add some additional information about what types of workloads you are trying to support. Active/Active replication is a hard problem with a lot of tradeoffs. It would be helpful to have more information about your specific usecase to inform those tradeoffs.

In our case, we currently use Redis to hold user session info for SSO purposes.

Because our setup is currently Active/Passive, when we do conduct a failover to disaster recovery site, all users will need to relogin. If there was an active/active setup for Valkey, it would be pretty great so there wouldnt be any downtime during a failover.

[btzq]

It might be this possible only on Proxy level. It make more complex if it start support in core Valkey code.

Im not quite sure how Redis Enterprise works, but im sure their version of Active/Active is done outside the core as well.

[madolson]

In our case, we currently use Redis to hold user session info for SSO purposes.

I presume that means you are using a hash or a string? Are you okay with a timestamp at the object level to determining which objects wins.

[Amitgb14]

@btzq , I think your problem can resolved by setup proxy in-between or setup slave on secondary region and any downtime you just failover, It's great if Valkey will think to support in future

[madolson]

@cjabrantes I skimmed the document quickly and don't know much about the technical details, so not sure how much it would be to implement this feature. I know that keyDB attaches a timestamp to each record that it uses for last writer wins, do you know if it replicates the entire object when mutations occur? That seems like a simple way to get last writer wins fairly quickly, but won't work well for certain workloads like distributed counters.

[mbfdias]

this would be a nice feature to add :) pity it's been categorized as a "not planned"

I'm unsure about the stability and future of KeyDB as is seems to be kinda dead and multi master is not a priority anywhere.

[madolson]

@mbfdias Less "not-planned" and more "need someone to implement it", which is hard given we are a community driven project.