# Single shard failing with snapshot

**URL:** <https://discuss.elastic.co/t/single-shard-failing-with-snapshot/344688>\
**Category:** Elasticsearch\
**Created:** [October 9, 2023, 6:41pm UTC](https://discuss.elastic.co/t/single-shard-failing-with-snapshot/344688 "2023-10-09T18:41:25Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Russell\_Fulton](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/russell_fulton/32/62888_2.png) [@Russell\_Fulton](https://discuss.elastic.co/u/Russell_Fulton)\
**Post date:** [October 9, 2023, 6:41pm UTC](https://discuss.elastic.co/t/single-shard-failing-with-snapshot/344688/1 "2023-10-09T18:41:25Z")

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I wish I knew why my backup system is so brittle : (

I have a single shard failing for the last couple of days - from kibana:

```auto
INTERNAL_SERVER_ERROR: UncategorizedExecutionException[Failed execution]; 
nested: ExecutionException[java.io.IOException: Input/output error: 
NIOFSIndexInput(path="/data/elasticsearch/security/nodes/0/indices/3dqdQFyJRyuUO_vVLon_WQ/2/index/_1bny.fdt")];
 nested: IOException[Input/output error: 
NIOFSIndexInput(path="/data/elasticsearch/security/nodes/0/indices/3dqdQFyJRyuUO_vVLon_WQ/2/index/_1bny.fdt")];
 nested: IOException[Input/output error]

```

Unfortunately it does not say which node the file is supposed to be on.

Should I delete the index and restore it from a good snapshot?

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**Author:** ![DavidTurner](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/davidturner/32/22453_2.png) [@DavidTurner](https://discuss.elastic.co/u/DavidTurner)\
**Post date:** [October 10, 2023, 4:40am UTC](https://discuss.elastic.co/t/single-shard-failing-with-snapshot/344688/2 "2023-10-10T04:40:32Z")

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> it does not say which node the file is supposed to be on.

I'm not familiar with this exact error message format, but assuming it means there's an `Input/output error` when reading `/data/elasticsearch/security/nodes/0/indices/3dqdQFyJRyuUO_vVLon_WQ/2/index/_1bny.fdt` then you're looking for a node holding a copy of shard 2 of the index with UUID `3dqdQFyJRyuUO_vVLon_WQ`, so look for that UUID in `GET /_cat/indices?h=uuid,index` and then look for the node in `GET /_cat/shards/$INDEX?s=s,p`. If it's snapshot-related then it's probably the node with the primary shard.

> [@Russell\_Fulton](#):
>
> Should I delete the index and restore it from a good snapshot?

Again assuming there's a problem reading `_1bny.fdt`, the error message `Input/output error` comes from the OS and normally means there's some problem with that node's storage. I'd suggest looking at its kernel logs with `dmesg` to confirm, and replace any faulty/suspect hardware before doing much more.

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<div class="post-metadata">

**Author:** ![Russell\_Fulton](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/russell_fulton/32/62888_2.png) [@Russell\_Fulton](https://discuss.elastic.co/u/Russell_Fulton)\
**Post date:** [October 10, 2023, 5:34am UTC](https://discuss.elastic.co/t/single-shard-failing-with-snapshot/344688/3 "2023-10-10T05:34:25Z")

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thanks David! Will track down which node is affected and see if i can figure out what is wrong with the disk.

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<div class="post-metadata">

**Author:** ![Russell\_Fulton](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/russell_fulton/32/62888_2.png) [@Russell\_Fulton](https://discuss.elastic.co/u/Russell_Fulton)\
**Post date:** [October 10, 2023, 9:53pm UTC](https://discuss.elastic.co/t/single-shard-failing-with-snapshot/344688/4 "2023-10-10T21:53:15Z")

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confirm disk errors - the hardware is old so this is not too surprising. Virtualising the server as it isn't worth replacing the disk.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [November 7, 2023, 9:53pm UTC](https://discuss.elastic.co/t/single-shard-failing-with-snapshot/344688/5 "2023-11-07T21:53:22Z")

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