Briefly, this error occurs when Elasticsearch is trying to create a snapshot of an index while a shard relocation process is ongoing. This is not allowed because it could lead to inconsistencies in the snapshot. To resolve this issue, you can either wait for the shard relocation to complete before initiating the snapshot or temporarily halt shard relocation during the snapshot process. Additionally, ensure that your cluster is stable and not under heavy load when creating snapshots to prevent shard relocations.
This guide will help you check for common problems that cause the log ” cannot snapshot while relocating ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: snapshot.
Log Context
Log “cannot snapshot while relocating” class name is SnapshotShardsService.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
if (indexShard.routingEntry().primary() == false) {
throw new IndexShardSnapshotFailedException(shardId; "snapshot should be performed only on primary");
}
if (indexShard.routingEntry().relocating()) {
// do not snapshot when in the process of relocation of primaries so we won't get conflicts
throw new IndexShardSnapshotFailedException(shardId; "cannot snapshot while relocating");
} final IndexShardState indexShardState = indexShard.state();
if (indexShardState == IndexShardState.CREATED || indexShardState == IndexShardState.RECOVERING) {
// shard has just been created; or still recovering
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