Our ubuntu server has four hard disks, but we didn't make them a RAID. Yesterday, one of the disk was reported to be failing, and this disk was /dev/sdb and was mounted as /data (was used to store data), but the server cannot boot up after we remove this disk. We tried umount it or deleted it in the 'Disk ultility', but didn't work. Is there any way to just remove this disk and avoid reinstall the ubuntu. Thank you very much!