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From "Albert P Tobey (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-8494) incremental bootstrap
Date Tue, 16 Dec 2014 22:45:14 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-8494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14249103#comment-14249103
] 

Albert P Tobey commented on CASSANDRA-8494:
-------------------------------------------

Neat idea. I think this would make a lot of sense to operators and provide visibility into
the rebuild process that's easy to understand (how many tokens are complete?).

Many of the customers I've talked to in the last few months will be very excited about this.
In one case, they want to attach ~70TB of very fast SSD. I explained everything to them, they're
still going to try.

Another client has more than 100 remote sites that store time-series data. They want to store
10-15TB per node on 15K SAS RAID10. It's the gear they can get and they have limited ability
to control power drops etc. in the remote sites, so density is really important to them.

My former employer was trying to run 8 x 3TB SATA. No matter how hard we fought for the right
drives, the incentives from the HW vendors etc. drove them to buy the big SATA drives.

I think ops folks will like this and there's an opportunity to use this feature to improve
the UX of bootstrap (by using token ranges to improve feedback to ops).

> incremental bootstrap
> ---------------------
>
>                 Key: CASSANDRA-8494
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8494
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Jon Haddad
>            Priority: Minor
>              Labels: density
>
> Current bootstrapping involves (to my knowledge) picking tokens and streaming data before
the node is available for requests.  This can be problematic with "fat nodes", since it may
require 20TB of data to be streamed over before the machine can be useful.  This can result
in a massive window of time before the machine can do anything useful.
> As a potential approach to mitigate the huge window of time before a node is available,
I suggest modifying the bootstrap process to only acquire a single initial token before being
marked UP.  This would likely be a configuration parameter "incremental_bootstrap" or something
similar.
> After the node is bootstrapped with this one token, it could go into UP state, and could
then acquire additional tokens (one or a handful at a time), which would be streamed over
while the node is active and serving requests.  The benefit here is that with the default
256 tokens a node could become an active part of the cluster with less than 1% of it's final
data streamed over.



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