>If we use IDE disk in RAID 1 then we need to restart system when one of disk become faulty. Suppose a raid device /dev/md0 exist that consist two ide disk /dev/sda and /dev/sdb and we set one of disk as fault
#mdadm mdadm /dev/md0 -f /dev/hda1
And followed by removing disk from raid array
#mdadm /dev/md0 -r /dev/hda1
After above steps we need to restart system .
With most hardware IDE RAID controllers, for a RAID 1 failure, you shutdown the machine, swap the drive, and restart. When the controller sees the new drive, it will begin to rebuild the array.
Note this is for IDE, which normally doesn't support hot swap. If it were SAS, SATA, or some SCSI backplanes, you could hotswap and leave the machine running.