In a particular case with one of our customers we encountered the reporting messages “Hard disk drive errors” in our logging and checked the solution with the customer, at first all seemed to be alright and no issues but this particular node would keep giving the event entries. From article https://support.citrix.com/s/article/CTX214458-netscaler-vpx-hard-drive-errors?language=en_US all indicates that the underlying hypervisor and this particular VM would be problematic. We’ve decided to rip the HA setup and remove the faulty node and re-add it with a fresh deployment, afterwards no error messages anymore, the storage itself for all the nodes encountered a previous failover and put in some corruption on this specific VM (others we’re save as to no issues or corruption).
Hope it helps.