# Huge amount of Space not released for \_recovery\_source
**URL:** https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477
**Category:** Elasticsearch
**Tags:** vector-search
**Created:** [March 5, 2025, 6:26pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477 "2025-03-05T18:26:25Z")
**Posts on this page:** 11
**Page:** 1
### Author:  [@Wei\_Chen](https://discuss.elastic.co/u/Wei_Chen)
#### Post date: [March 5, 2025, 6:26pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/1 "2025-03-05T18:26:25Z")
Hi, I am trying to optimize my dense vector space usage of the `_source` field but haven't got any luck so far. I tried with turning on synthetic source, but then I observed that I now see a new `_recovery_source` field taking 4x of the space of my vector. I attempted to both shortening the soft delete retention using `index.soft_deletes.retention_lease.period`, and force-merging my index using
```auto
client.indices.forcemerge(index=my_index)
```
None of these methods helps - the `_recovery_source` remains even after a few days the index get force-merged. What are things I should look into here?
This is costing us a horrible amount of budget b/c Elasticsearch is storing 5x what it's supposed to store and so far there's no obvious documentation optimizing this. We are consider other Vector DB providers if we couldn't solve this issue.
Appendix:
My server version: v8.17.2
Disk usage breakdown:
```auto
{
"_shards": {
"total": 1,
"successful": 1,
"failed": 0
},
"54.346_embedding_1740616609": {
"store_size": "11.9mb",
"store_size_in_bytes": 12546243,
"all_fields": {
"total": "11.9mb",
"total_in_bytes": 12527444,
"inverted_index": {
"total": "12.4kb",
"total_in_bytes": 12753
},
"stored_fields": "9mb",
"stored_fields_in_bytes": 9444229,
"doc_values": "446b",
"doc_values_in_bytes": 446,
"points": "613b",
"points_in_bytes": 613,
"norms": "0b",
"norms_in_bytes": 0,
"term_vectors": "0b",
"term_vectors_in_bytes": 0,
"knn_vectors": "2.9mb",
"knn_vectors_in_bytes": 3069403
},
"fields": {
"__soft_deletes": {
"total": "18b",
"total_in_bytes": 18,
"inverted_index": {
"total": "0b",
"total_in_bytes": 0
},
"stored_fields": "0b",
"stored_fields_in_bytes": 0,
"doc_values": "18b",
"doc_values_in_bytes": 18,
"points": "0b",
"points_in_bytes": 0,
"norms": "0b",
"norms_in_bytes": 0,
"term_vectors": "0b",
"term_vectors_in_bytes": 0,
"knn_vectors": "0b",
"knn_vectors_in_bytes": 0
},
"_id": {
"total": "20.5kb",
"total_in_bytes": 21025,
"inverted_index": {
"total": "10.4kb",
"total_in_bytes": 10667
},
"stored_fields": "10.1kb",
"stored_fields_in_bytes": 10358,
"doc_values": "0b",
"doc_values_in_bytes": 0,
"points": "0b",
"points_in_bytes": 0,
"norms": "0b",
"norms_in_bytes": 0,
"term_vectors": "0b",
"term_vectors_in_bytes": 0,
"knn_vectors": "0b",
"knn_vectors_in_bytes": 0
},
"_primary_term": {
"total": "0b",
"total_in_bytes": 0,
"inverted_index": {
"total": "0b",
"total_in_bytes": 0
},
"stored_fields": "0b",
"stored_fields_in_bytes": 0,
"doc_values": "0b",
"doc_values_in_bytes": 0,
"points": "0b",
"points_in_bytes": 0,
"norms": "0b",
"norms_in_bytes": 0,
"term_vectors": "0b",
"term_vectors_in_bytes": 0,
"knn_vectors": "0b",
"knn_vectors_in_bytes": 0
},
"_recovery_source": {
"total": "8.9mb",
"total_in_bytes": 9416321,
"inverted_index": {
"total": "0b",
"total_in_bytes": 0
},
"stored_fields": "8.9mb",
"stored_fields_in_bytes": 9416321,
"doc_values": "0b",
"doc_values_in_bytes": 0,
"points": "0b",
"points_in_bytes": 0,
"norms": "0b",
"norms_in_bytes": 0,
"term_vectors": "0b",
"term_vectors_in_bytes": 0,
"knn_vectors": "0b",
"knn_vectors_in_bytes": 0
},
"_seq_no": {
"total": "1012b",
"total_in_bytes": 1012,
"inverted_index": {
"total": "0b",
"total_in_bytes": 0
},
"stored_fields": "0b",
"stored_fields_in_bytes": 0,
"doc_values": "399b",
"doc_values_in_bytes": 399,
"points": "613b",
"points_in_bytes": 613,
"norms": "0b",
"norms_in_bytes": 0,
"term_vectors": "0b",
"term_vectors_in_bytes": 0,
"knn_vectors": "0b",
"knn_vectors_in_bytes": 0
},
"_source": {
"total": "17.1kb",
"total_in_bytes": 17550,
"inverted_index": {
"total": "0b",
"total_in_bytes": 0
},
"stored_fields": "17.1kb",
"stored_fields_in_bytes": 17550,
"doc_values": "0b",
"doc_values_in_bytes": 0,
"points": "0b",
"points_in_bytes": 0,
"norms": "0b",
"norms_in_bytes": 0,
"term_vectors": "0b",
"term_vectors_in_bytes": 0,
"knn_vectors": "0b",
"knn_vectors_in_bytes": 0
},
"_version": {
"total": "29b",
"total_in_bytes": 29,
"inverted_index": {
"total": "0b",
"total_in_bytes": 0
},
"stored_fields": "0b",
"stored_fields_in_bytes": 0,
"doc_values": "29b",
"doc_values_in_bytes": 29,
"points": "0b",
"points_in_bytes": 0,
"norms": "0b",
"norms_in_bytes": 0,
"term_vectors": "0b",
"term_vectors_in_bytes": 0,
"knn_vectors": "0b",
"knn_vectors_in_bytes": 0
},
"content_id": {
"total": "2kb",
"total_in_bytes": 2086,
"inverted_index": {
"total": "2kb",
"total_in_bytes": 2086
},
"stored_fields": "0b",
"stored_fields_in_bytes": 0,
"doc_values": "0b",
"doc_values_in_bytes": 0,
"points": "0b",
"points_in_bytes": 0,
"norms": "0b",
"norms_in_bytes": 0,
"term_vectors": "0b",
"term_vectors_in_bytes": 0,
"knn_vectors": "0b",
"knn_vectors_in_bytes": 0
},
"embedding": {
"total": "2.9mb",
"total_in_bytes": 3069403,
"inverted_index": {
"total": "0b",
"total_in_bytes": 0
},
"stored_fields": "0b",
"stored_fields_in_bytes": 0,
"doc_values": "0b",
"doc_values_in_bytes": 0,
"points": "0b",
"points_in_bytes": 0,
"norms": "0b",
"norms_in_bytes": 0,
"term_vectors": "0b",
"term_vectors_in_bytes": 0,
"knn_vectors": "2.9mb",
"knn_vectors_in_bytes": 3069403
}
}
}
}
```
---
### Author:  [@RainTown](https://discuss.elastic.co/u/RainTown)
#### Post date: [March 5, 2025, 7:04pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/2 "2025-03-05T19:04:54Z")
What license do you have ?
Reason I ask is the synthetic source licensing changed in 8.17. It’s in the release notes.
---
### Author:  [@Wei\_Chen](https://discuss.elastic.co/u/Wei_Chen)
#### Post date: [March 5, 2025, 8:20pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/3 "2025-03-05T20:20:39Z")
Hi Kevin, thanks for the quick response! We are on 'Monthly Enterprise' plan and our subscription is 'Enterprise with premium support'. Is that the 'license' you are asking about?
---
### Author:  [@Wei\_Chen](https://discuss.elastic.co/u/Wei_Chen)
#### Post date: [March 5, 2025, 8:24pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/4 "2025-03-05T20:24:37Z")
Additionally, we attempted to use synthetic source mode and it did successfully removed `_source` field. However, it's creating another `_recovery_source` field which we couldn't manage to remove properly
---
### Author:  [@nhat](https://discuss.elastic.co/u/nhat)
#### Post date: [March 5, 2025, 8:25pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/5 "2025-03-05T20:25:40Z")
Hello @Wei_Chen
This is a known issue. See: `https://github.com/elastic/elasticsearch/issues/116726` and `https://github.com/elastic/elasticsearch/issues/41628`.
In your setup, the segment is currently fully merged when the retention lease is advanced. However, if more data is ingested and that segment becomes mergeable again with other new segments, the `_recovery_source` will be eventually pruned by merges. There is a case where the segment is very large (\>5GB) and fully merged, the `_recovery_source` won't be removed.
In Elasticsearch 8.18 or later, you can disable `_recovery_source` via a new index setting: `index.recovery.use_synthetic_source`. See: `https://github.com/elastic/elasticsearch/pull/114618/`
---
### Author:  [@RainTown](https://discuss.elastic.co/u/RainTown)
#### Post date: [March 5, 2025, 8:47pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/6 "2025-03-05T20:47:51Z")
yes. Was just a guess. wrong in this case.
---
### Author:  [@Wei\_Chen](https://discuss.elastic.co/u/Wei_Chen)
#### Post date: [March 5, 2025, 9:25pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/7 "2025-03-05T21:25:46Z")
Thank you Nhat! Our version is 18.7.2 and we couldn't seem to be able to upgrade to 8.18. The only provided upgrade option is 18.7.3. What should we do to get it upgrade?
---
### Author:  [@Wei\_Chen](https://discuss.elastic.co/u/Wei_Chen)
#### Post date: [March 5, 2025, 9:29pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/8 "2025-03-05T21:29:42Z")
It's also fine if you've got any suggestions within the context of 18.7 (so that we don't have to upgrade) - for example, can I merge twice and trick the system to purge the larger `_recovery_source` field?
---
### Author:  [@leandrojmp](https://discuss.elastic.co/u/leandrojmp)
#### Post date: [March 5, 2025, 9:30pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/9 "2025-03-05T21:30:52Z")
> [@Wei\_Chen](#):
>
> What should we do to get it upgrade?
You need to wait for it to be released, 8.18 was not released yet.
---
### Author:  [@Wei\_Chen](https://discuss.elastic.co/u/Wei_Chen)
#### Post date: [March 11, 2025, 9:41pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/10 "2025-03-11T21:41:46Z")
Great to know, thanks @leandrojmp . @nhat I'm wondering when could we expect the release? This issue is costing us a lot in storage, it'd be great to have an ETA on this
---
### Author:  [@Wei\_Chen](https://discuss.elastic.co/u/Wei_Chen)
#### Post date: [April 2, 2025, 9:14pm UTC](https://discuss.elastic.co/t/huge-amount-of-space-not-released-for-recovery-source/375477/11 "2025-04-02T21:14:39Z")
@nhat would you mind kindly provide a timeline for 8.18 update? We are spending over $2k per month and is reaching the limit, and the next tier will 2x the cost. It doesn't make sense for us to continue to hold on this plan because the storage should have taken only 30% of the current size.