Cool, good to know. Do you know this is still true for 3.11.1?
> Am 03.02.2018 um 08:19 schrieb Oleksandr Shulgin
> <oleksandr.shul...@zalando.de>:
>
> On 3 Feb 2018 02:42, "Kyrylo Lebediev" <kyrylo_lebed...@epam.com> wrote:
> Thanks, Oleksandr,
> In my case I'll need to replace all nodes in the cluster (one-by-one), so
> streaming will introduce perceptible overhead.
> My question is not about data movement/copy itself, but more about all this
> token magic.
>
> Okay, let's say we stopped old node, moved data to new node.
> Once it's started with auto_bootstrap=false it will be added to the cluster
> like an usual node, just skipping streaming stage, right?
> For a cluster with vnodes enabled, during addition of new node its token
> ranges are calculated automatically by C* on startup.
>
> So, how will C* know that this new node must be responsible for exactly the
> same token ranges as the old node was?
> How would the rest of nodes in the cluster ('peers') figure out that old node
> should be replaced in ring by the new one?
> Do you know about some limitation for this process in case of C* 2.1.x with
> vnodes enabled?
>
> A node stores its tokens and host id in the system.local table. Next time it
> starts up, it will use the same tokens as previously and the host id allows
> the rest of the cluster to see that it is the same node and ignore the IP
> address change. This happens regardless of auto_bootstrap setting.
>
> Try "select * from system.local" to see what is recorded for the old node.
> When the new node starts up it should log "Using saved tokens" with the list
> of numbers. Other nodes should log something like "ignoring IP address
> change" for the affected node addresses.
>
> Be careful though, to make sure that you put the data directory exactly where
> the new node expects to find it: otherwise it might just join as a brand new
> one, allocating new tokens. As a precaution it helps to ensure that the
> system user running the Cassandra process has no permission to create the
> data directory: this should stop the startup in case of misconfiguration.
>
> Cheers,
> --
> Alex
>
