Error 823 and no connection
SQLIOSIM has identified at least one disk that is failing. You could look in the system event log for errors or warnings that concern the same disk subsystem's IO. The active SQL Server errorlog (C:\Program Files\Microsoft SQL Server\MSSQLx\MSSQL\Log, which is a text file), will also contain the 823 error. The 823 error being raised in the system event log could concern a driver. If SQL Server is failing to start, one of the system databases' disk(s) is likely to have failed.

Failing over SQL Server resets the driver and sets up a new IO path, but failover clustering is designed for high availability, not fault tolerance. Each time an IO failure occurs, a database can become corrupted, which database backups can backup. You should restore your backups on a DR server, run checkdb upon the restored backups. In the meanwhile, ask your system administrator to resolve the disk IO failures. The longer you wait, the higher the risk of corruption being backed up.