mdadm: cannot open /dev/sda1: Device or resource busy

Build soft raid Resource occupancy is found during , This partition does not Mount

[[email protected] dev]# mdadm --create /dev/md0 --level=1 --raid-disks=2 /dev/sda1 missing
 mdadm: cannot open /dev/sda1: Device or resource busy

Check whether the DM of

[[email protected] ~]# dmsetup info
Name:              ddf1_Drive 2
State:             ACTIVE
Read Ahead:        256
Tables present:    LIVE
Open count:        0
Event number:      0
Major, minor:      253, 0
Number of targets: 1
UUID: DMRAID-ddf1_Drive 2
 

[[email protected] ~]# dmsetup ls --tree
ddf1_Drive 2 (253:0)
 └─ (8:0)

[[email protected] dev]# dmsetup ls
ddf1_Drive 2    (253:0)

stay /dev Make sure 253:0 and 8:0 Mapped devices

Sure enough sda It's occupied , Need to put this dm Delete the

[[email protected] dev]# ls -l /dev

brw-rw----.  1 root disk    253,   0 May 31 08:35 dm-0
brw-rw----.  1 root disk      8,   0 May 31 08:35 sda

Put this dm Delete , Found not found

[[email protected] dev]# dmsetup remove ddf1_Drive 2
device-mapper: remove ioctl on ddf1_Drive  failed: No such device or address
Command failed
 

Name has spaces , So add a double quotation mark

[[email protected] dev]# dmsetup remove "ddf1_Drive 2"
[[email protected] dev]#  dmsetup ls
No devices found
 

dm It will be normal after deletion ！