Running several Solr servers in Cloud-cluster (zkHost set on the Solr servers).
Several collections with several slices and one replica for each slice (each slice has two shards)
Basically we want let our system delete an entire collection. We do this by trying to delete each and every shard under the collection. Each shard is deleted one by one, by doing CoreAdmin-UNLOAD-requests against the relevant Solr
The delete/unload succeeds, but in like 10% of the cases we get errors on involved Solr servers, right around the time where shard/cores are deleted, and we end up in a situation where ZK still claims (forever) that the deleted shard is still present and active.
Form here the issue is easilier explained by a more concrete example:
- 7 Solr servers involved
- Several collection a.o. one called "collection_2012_04", consisting of 28 slices, 56 shards (remember 1 replica for each slice) named "collection_2012_04_sliceX_shardY" for all pairs in
- Each Solr server running 8 shards, e.g Solr server #1 is running shard "collection_2012_04_slice1_shard1" and Solr server #7 is running shard "collection_2012_04_slice1_shard2" belonging to the same slice "slice1".
When we decide to delete the collection "collection_2012_04" we go through all 56 shards and delete/unload them one-by-one - including "collection_2012_04_slice1_shard1" and "collection_2012_04_slice1_shard2". At some point during or shortly after all this deletion we see the following exceptions in solr.log on Solr server #7
Im not sure exactly how to interpret this, but it seems to me that some recovery job tries to recover collection_2012_04_slice1_shard2 on Solr server #7 from collection_2012_04_slice1_shard1 on Solr server #1, but fail because Solr server #1 answers back that it doesnt run collection_2012_04_slice1_shard1 (anymore).
This problem occurs for serveral (in this conrete test for 4) of the 28 slice pairs. For those 4 shards the end result is that /node_states/solr_server_X:8983_solr in ZK still contains information about the shard being running and active. E.g. /node_states/solr_server_7:8983_solr still contains
and that CloudState therefore still reports that those shards are running and active - but thay are not. A.o. I have noticed that "collection_2012_04_slice1_shard2" HAS been removed from solr.xml on Solr server #7 (we are running with persistent="true")
Any chance that this bug is fixed in a later revision (than one from 29/2-2012) of 4.0-SNAPSHOT?
If not we need to get it fixed, I believe.