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https://issues.apache.org/jira/browse/ACCUMULO-3842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14559145#comment-14559145
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Josh Elser commented on ACCUMULO-3842:
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{quote}
bq. Loss of ZooKeeper doesn't lose table configuration and users
Is this a genuine problem for users?
{quote}
IMO, we don't have enough rigor here to actually make me comfortable to tell
someone that we have the means to backup and restore ZooKeeper. I know we have
some tools, but I don't know how much this is actually used and tested.
Ideally, it would be better if we can have a single way to backup data for an
Accumulo cluster and later restore it (import/export table is a likely
candidate for simplicity). Perhaps removing table configuration in ZK isn't a
good idea, but I definitely think users information should not be stored in ZK.
> [UMBRELLA] Remove non-transient data from ZooKeeper
> ---------------------------------------------------
>
> Key: ACCUMULO-3842
> URL: https://issues.apache.org/jira/browse/ACCUMULO-3842
> Project: Accumulo
> Issue Type: Improvement
> Components: client, tserver
> Reporter: Josh Elser
> Fix For: 1.8.0
>
>
> Wanted to start brainstorming about this.
> We store a lot of persistent data in ZooKeeper that would better stored in
> something backed by HDFS. ZooKeeper can be a very convenient place to store
> persisted data so that it's available to all nodes, but it comes at a price
> and often must be asynchronously accessed to achieve good performance.
> * Table/Namespace configuration
> * Users/Authorizations
> * Problem reports (maybe?)
> * System configuration overrides (maybe?)
> Some benefits we'd see from this:
> * Loss of ZooKeeper doesn't lose table configuration and users.
> * Greatly reduce zookeeper watchers (assume
> watchers=50*num_tables*num_tservers)
> * Consistent updates of table constraints and all other table properties
> The last note is the most important one IMO. The number of test issues alone
> that we've had with constraints not being seen on all servers are bound to
> affect users.
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