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Re: RangeAwareCompaction for manual token management


I've had similar thoughts in the past about RACS and manual tokens. I think
it would be a good idea to be able to split it based on some configurable
factor other than vnodes. I think Marcus may have already addressed this to
some extent as well but if not it's theoretically possible.


On 20 July 2018 at 07:34, Carl Mueller <carl.mueller@xxxxxxxxxxxxxxx.invalid
> wrote:

> I don't want to comment on the 10540 ticket since it seems very well
> focused on vnode-aligned sstable partitioning and compaction. I'm pretty
> excited about that ticket. RACS should enable:
>
> - smaller scale LCS, more constrained I/O consumption
> - less sstables to hit in read path
> - multithreaded/multiprocessor compactions and even serving of data based
> on individual vnode or pools of vnodes
> - better alignment of tombstones with data they should be
> nullifying/eventually removing
> - repair streaming efficiency
> - backups have more granularity for not uploading sstables that didn't
> change for the range since last backup snapshot
>
> There is ongoing discussions as to using Priam for cluster management where
> I am, and as I understand it (superficially) Priam does not use vnodes and
> use manual tokens, and expands via node multiples. I believe it has certain
> advantages over vnodes including expanding by multiple machines at once,
> backups could possibly do (nodecount / RF) number of nodes for data backups
> rather than the mess of vnodes where you have to do basically all of them.
>
> But we could still do some divisor split of the manual range and apply RACS
> to that. I guess this would be vnode-lite. We could have some number like
> 100 subranges on a  node and expansion might just involve temporary lower
> bound count of subranges until the sstables can be reprocessed to the
> typical subrange count.
>
> Is this theoretically correct, or are there glaring things I might have
> missed with respect to RACS-style compaction and manual tokens?
>


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