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From Shalin Shekhar Mangar <>
Subject Re: Clone (or Restore) Solrcloud
Date Mon, 03 Feb 2014 08:02:59 GMT
Hi David,

The parent metadata persists only until the sub-shards become active.
Actually the logic to make the sub-shards active depends on knowing
when all 'sibling' sub-shards' replicas have recovered successfully.
We store the parent to make that easier to look up. Once all replicas
of all sub-shards have recovered, the shard states are updated. The
'updateshardstate' command also removes the 'parent' key from the
sub-shards while switching them to 'active'.

If you're seeing the 'parent' key on a 'active' sub-shard then it may
be a bug. Please paste your clusterstate and I'll look into why it was
left over.

On Mon, Feb 3, 2014 at 10:19 AM, David Smiley (
<> wrote:
> I think I figured this out; I hope people find this useful..
> It may not be possible to declare what the hash ranges are when you create
> the collection, but you *can* do so when you split via the 'ranges'
> parameter, which is a comma-delimited list. So this means you can create a
> new collection with one shard and then immediately split it to the desired
> ranges to line up with that of your backup.  I also observed that if you
> create a collection and then split every shard (in 2), it will result in an
> equivalent collection to one that was created with twice as many shards to
> begin with.  I hoped that was so and verified the ranges end up being the
> same both ways.
> The only thing that seems like it may be benign but not 100% certain is that
> if you split a shard, the new shards have a 'parent' reference to the name
> of the shard it was split from.  And even if you delete that parent shard
> (since it's not needed anymore; it becomes inactive).  I'm not sure why this
> metadata is recorded because, at least after the split, I can't see why it's
> pertinent to anything.
> ~ David
> David Smiley ( wrote
>> Hi,
>> I'm attempting to come up with a SolrCloud restore / clone process for
>> either recover to a known good state or to clone the environment for
>> experimentation.  At the moment my process involves either creating a new
>> zookeeper environment or at least deleting the existing Collection so that
>> I can create a new one.  This works; I use the Core API; the first command
>> defines the collection parameters, and I invoke it once for each replica.
>> I don't use the Collection API because I want SolrCloud to go off trying
>> to create all the replicas -- I know where each one is pre-positioned.
>> What I'm concerned about is what happens once I start wanting to use Shard
>> splitting, *especially* if I don't want to split all shards because shards
>> are uneven due to custom routing (e.g. id:"customer!myid").  In this case
>> I don't know how to create the collection with the hash ranges post-shard
>> split.  Solr doesn't have an API for me to explicitly say what the hash
>> ranges should be on each shard (to match up with a backup).  And I'm
>> concerned about undocumented pitfalls that may exist in manually
>> constructing a clusterstate.json, as another approach.
>> Any ideas?
>> ~ David
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Shalin Shekhar Mangar.

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