That could be caused by a number of things. Maybe the .rdb file for that redis instance is corrupted and needs to be re-created. You would do that by stopping redis then finding the corresponding .rdb file for it and deleting it, then starting it again. Example...
For collectorredis on the localhost collector:
/opt/serviced/var/volumes/6zbnssjd86cva5rtoa5ifuhsa/localhost/localhost_collectorredis/dump.rdbFor the main redis instance:/opt/serviced/var/volumes/6zbnssjd86cva5rtoa5ifuhsa/redis/dump.rdbIf the redis instance is for a remote collector on a delegate host it may be stored on that host's filesystem rather than inside the main serviced volume if NFS / DFS isn't mounted on the remote host.
If it's a collectorredis that's failing it might be maxed out with metrics. You could check the graphs for it in Control Center to see if the queue graph shows that it's filled up. If it's the main redis instance you could check the same thing on it's graphs. If it's getting backed up it means that there's likely a problem somewhere in the pipeline.