We saw a case where the recovery stats reported `recovered_bytes` greater than `length_in_bytes` for one file:

```
GET /_recovery?detailed

200 OK
...
{
  "name": "_buk.fdt",
  "length_in_bytes": 26891307173,
  "reused": false,
  "recovered_in_bytes": 35324928266,
  "recovered_from_snapshot_in_bytes": 8433621093
}
...
```

NB `35324928266 == 26891307173 + 8433621093`

This causes Elasticsearch to compute a negative value for the reserved space on the target node of this recovery, which prevents stats APIs from working. This appears to be caused by a network-level failure which triggers a retry without first cancelling an ongoing download of a different file with the same name from the snapshot repository.

---

### Workaround

Restart the target node to clear these stats.
server/src/main/java/org/elasticsearch/index/shard/IndexShard.java
/**
     * Executes a scheduled refresh if necessary.
     *
     * @return <code>true</code> iff the engine got refreshed otherwise <code>false</code>
     */
    public boolean scheduledRefresh() {
        verifyNotClosed();
        boolean listenerNeedsRefresh = refreshListeners.refreshNeeded();
        if (isReadAllowed() && (listenerNeedsRefresh || getEngine().refreshNeeded())) {
            if (listenerNeedsRefresh == false 
                && isSearchIdle()
                && indexSettings.isExplicitRefresh() == false
                && active.get()) { 
                
                
                
                final Engine engine = getEngine();
                engine.maybePruneDeletes(); 
                setRefreshPending(engine);
                return false;
            } else {
                if (logger.isTraceEnabled()) {
                    logger.trace("refresh with source [schedule]");
                }
                return getEngine().maybeRefresh("schedule");
            }
        }
        final Engine engine = getEngine();
        engine.maybePruneDeletes(); 
        return false;