OpsCenter reports "Cannot run anti-entropy repair on tables with NodeSync enabled"

Question

I'm monitoring a DSE cluster and I see the following problem:

As you can see it says that the Repair is currently failing, this value keeps going up with time. Can someone explain to me what's happening in here? In the Opscenter logs I can only find this error:

Is this related to the problem?

Checked logs and documentation.

Answer 1

In DSE there are two ways to perform anti-entropy repair:

1. Traditional Cassandra repair using nodetool repair command
2. NodeSync that is often faster and more intelligent (see this blog post for more details)

But you couldn't use traditional repair on the tables where NodeSync is enabled. So you need to click on settings icon for Repair and disable running it on the keyspaces/tables with NodeSync enabled.

Answer 2

To add to Alex Ott's excellent response, NodeSync is a new feature in DataStax Enterprise which runs a repair continuously in the background using the same mechanism as read-repairs and replaces the traditional anti-entropy repairs.

The OpsCenter Repair Service will skip repairs on tables which have NodeSync enabled because it isn't possible to run traditional repairs on them as I've explained in this post -- https://community.datastax.com/questions/3879/.

If NodeSync was enabled on a table while a repair on that same table was already scheduled and running, it would explain why you're seeing error messages.

You can stop the errors from being generated by explicitly excluding the keyspace(s) or table(s) from subrange repairs with:

[repair_service]
ignore_keyspaces=ks_name_1,ks_name_2
ignore_tables=ks_name_3.table_name_1,ks_name_3.table_name_2