Raid 1+0 MDADM question
 

Hi,
I have a server running 4 x 1TB drives currently in RAID 10 md0 - (sda2, sdb1, sdc1, sdd1).
Yesterday, the server started to run a lot slower than usual, and now Ubuntu has shown an error stating that Disk Drive Failure is Immenent (on sdb1).
Should I just flag sdb1 as failed, remove it from md0, power down system, and replace the drive with a blank disk then rebuild?
I am unsure as to the order I should be doing things to rectify this.
Thanks

Run a smart check on it, you can try to remove and readd but your steps are correct