What does this error tell you?
Server: Msg 823, Level 24, State 1, Line 3
I/O error 121(The semaphore timeout period has expired.) detected during read of BUF pointer = 0x14235a40, page ptr = 0x15602000, pageid = (0x3:0xb88), dbid = 4, status = 0x801, file = ...
This occurred after I screwed up by adding a SCSI device with the same SCSI ID as I was already using. However, the disk check did not find any errors. Obviously I'm looking for an answer other than "restore from backup".