Failure Predicted instruction

Hello, 

This is my situation 

RAID5 ARRAY 

T420 

PRECH710

Physical Disk 0:1:0 Online Spun Up
Physical Disk 0:1:1 Online Spun Up Failure Predicted
Physical Disk 0:1:2 Online Spun Up
Physical Disk 0:1:4 Ready Spun Up GLOBAL HOT SPARE
Physical Disk 0:1:5 Online Spun Up

What do I need to do ?

execute  -OFF -  Physical Disk 0:1:1

then I will see rebuild option to execute on  Physical Disk 0:1:4  ? 

I don`t sure because the OPEN MANAGE send me alert 

"Making a physical disk offline may result in data loss. Are you sure you want to offline this physical disk?"

When I trying to execute  -OFF -  Physical Disk 0:1:1

HELP