The Redis Software UI alerts of "Unable to write to disk due to reaching disk I/O limit" in nodes summary page

Question

The admin UI alerts of "Unable to write to disk due to reaching disk I/O limit" in the nodes summary page

Answer

The alert is about the disk I/O limit, not the storage limit. The disk may not be full but cannot keep up its speed. This may happen, for instance, if all the shards in a node have persistence via AOF enabled. It has something to do with the underlying hardware.