Why is that when a single disk fails from a RAID 6 setup MS SQL 2014 database corrupts with the following error:
DESCRIPTION: SQL Server detected a logical consistency-based I/O error: torn page (expected signature: 0x55555555; actual signature: 0xad191b0d). It occurred during a read of page (1:144366313) in database ID 19 at offset 0x0001135b5d2000 in file 'D:\MSSQL12.LIST133\MSSQL\DATA\test.mdf'. Additional messages in the SQL Server error log or system event log may provide more detail. This is a severe error condition that threatens database integrity and must be corrected immediately. Complete a full database consistency check (DBCC CHECKDB). This error can be caused by many factors; for more information, see SQL Server Books Online.
The RAID 6 status is healthy and hasn't change even with one disk failed (the issue should appear when 3 DISKs fail). How does the SQL knows what is going on with the DISK since it is not a software RAID 6? There is a seperate controller and a storage.
Also what is the point of having spare disks in the RAID if the SQL is going to corrupt anyway? How can I avoid this?
Best Answer
Firstly you should change your database page verification setting from tornpage to checksum to have more reliable identification of database corruption.
secondly SQL Server has detected an I/O error - not surprising if an entire disk failed (or was removed while you tested your test db). - Anyway you won't know if the database is corrupt until you complete the recommended action - DBCC CHECKDB