# Primary and replica shard allocation on a single node cluster

**URL:** <https://discuss.elastic.co/t/primary-and-replica-shard-allocation-on-a-single-node-cluster/89283>\
**Category:** Elasticsearch\
**Created:** [June 13, 2017, 11:16pm UTC](https://discuss.elastic.co/t/primary-and-replica-shard-allocation-on-a-single-node-cluster/89283 "2017-06-13T23:16:59Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![sandsbl](https://avatars.discourse-cdn.com/v4/letter/s/b487fb/32.png) [@sandsbl](https://discuss.elastic.co/u/sandsbl)\
**Post date:** [June 13, 2017, 11:16pm UTC](https://discuss.elastic.co/t/primary-and-replica-shard-allocation-on-a-single-node-cluster/89283/1 "2017-06-13T23:16:59Z")

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I am planning to use Elasticsearch within a single-node cluster. The other servers on our network are tasked for different resource-intensive tasks so adding additional nodes may not be feasible. If I configure `path.data` to multiple paths spread out over different physical disks (say 2 for example), then configure a new index with `number_of_shards : 1` and `number_of_replicas : 1`, will elasticsearch automatically separate the primary shard and replica shard out over different disks on the same node, or must this allocation be configured? I would like to do this to at least provide some redundancy against hard drive failure (i.e. be RAID-like) if we cannot run with more than a single-node cluster.

Separately, even if the primary and replica shards are spread between different disks, can the overall cluster status ever be **green**?

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**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\
**Post date:** [June 13, 2017, 11:20pm UTC](https://discuss.elastic.co/t/primary-and-replica-shard-allocation-on-a-single-node-cluster/89283/2 "2017-06-13T23:20:30Z")

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> [@sandsbl](#):
>
> will elasticsearch automatically separate the primary shard and replica shard out over different disks on the same node, or must this allocation be configured?

It'll do it automatically.

> [@sandsbl](#):
>
> Separately, even if the primary and replica shards are spread between different disks, can the overall cluster status ever be green?

Yes because everything will be assigned.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 11, 2017, 11:20pm UTC](https://discuss.elastic.co/t/primary-and-replica-shard-allocation-on-a-single-node-cluster/89283/3 "2017-07-11T23:20:40Z")

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