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

Ahojte, chci si vytvořit jednoduchý raid 1 z disků /dev/sda1 a /dev/sdb1 na linux ubuntu a nedaří se mi to. Nedělám to poprvé a navíc postupuji i dle návodu na tomto webu. Dostávám chybu mdadm: cannot open /dev/sda1: Device or resource busy a z nějakého mně neznámého důvodu neproběhne vytvoření oddílů na disku /dev/sdb dle disku /dev/sda příkazem sfdisk -d /dev/sda | sfdisk /dev/sdb. Níže dávám výpis z bashe. Díky za pomoc

[root@server7 ~]# gdisk /dev/sda
GPT fdisk (gdisk) version 0.8.6

Partition table scan:
  MBR: MBR only
  BSD: not present
  APM: not present
  GPT: present

Found valid MBR and GPT. Which do you want to use?
 1 - MBR
 2 - GPT
 3 - Create blank GPT

Your answer: 2
Using GPT and creating fresh protective MBR.

Command (? for help): n
Partition number (1-128, default 1):  
First sector (34-1953525134, default = 2048) or {+-}size{KMGTP}: 
Last sector (2048-1953525134, default = 1953525134) or {+-}size{KMGTP}: 
Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300): fd00
Changed type of partition to 'Linux RAID'

Command (? for help): w

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!

Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to /dev/sda.
Warning: The kernel is still using the old partition table.
The new table will be used at the next reboot.
The operation has completed successfully.
[root@server7 ~]# lsblk
NAME      MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda         8:0    0 931,5G  0 disk  
└─sda1      8:1    0 931,5G  0 part  
  └─md127   9:127  0 931,4G  0 raid1 
sdb         8:16   0 931,5G  0 disk  
sdc         8:32   0 596,2G  0 disk  
├─sdc1      8:33   0   953M  0 part  /boot
├─sdc2      8:34   0    28G  0 part  /
└─sdc3      8:35   0   7,5G  0 part  [SWAP]
sdd         8:48   0 465,8G  0 disk  
└─sdd1      8:49   0 465,8G  0 part
[root@server7 ~]# sfdisk -d /dev/sda | sfdisk /dev/sdb
Checking that no-one is using this disk right now ...
OK

Disk /dev/sdb: 121601 cylinders, 255 heads, 63 sectors/track
Old situation:
Units: cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdb1          0+ 121601- 121602- 976762583+  ee  GPT
/dev/sdb2          0       -       0          0    0  Empty
/dev/sdb3          0       -       0          0    0  Empty
/dev/sdb4          0       -       0          0    0  Empty
New situation:
Units: sectors of 512 bytes, counting from 0

   Device Boot    Start       End   #sectors  Id  System
/dev/sdb1             1 1953525167 1953525167  ee  GPT
/dev/sdb2             0         -          0   0  Empty
/dev/sdb3             0         -          0   0  Empty
/dev/sdb4             0         -          0   0  Empty
Warning: partition 1 does not end at a cylinder boundary
Warning: no primary partition is marked bootable (active)
This does not matter for LILO, but the DOS MBR will not boot this disk.
Successfully wrote the new partition table

Re-reading the partition table ...

If you created or changed a DOS partition, /dev/foo7, say, then use dd(1)
to zero the first 512 bytes:  dd if=/dev/zero of=/dev/foo7 bs=512 count=1
(See fdisk(8).)
[root@server7 ~]# lsblk
NAME      MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda         8:0    0 931,5G  0 disk  
└─sda1      8:1    0 931,5G  0 part  
  └─md127   9:127  0 931,4G  0 raid1 
sdb         8:16   0 931,5G  0 disk  
sdc         8:32   0 596,2G  0 disk  
├─sdc1      8:33   0   953M  0 part  /boot
├─sdc2      8:34   0    28G  0 part  /
└─sdc3      8:35   0   7,5G  0 part  [SWAP]
sdd         8:48   0 465,8G  0 disk  
└─sdd1      8:49   0 465,8G  0 part 
[root@server7 ~]# mdadm --create /dev/md0 --level=1 --raid-disks=2 /dev/sda1 /dev/sdb1
mdadm: cannot open /dev/sda1: Device or resource busy

ODPOVĚĎ

Ahoj,

dle všeho disk /dev/sda má stále nastaveno, že se jedná o typ "linux raid member" s md127 - bude třeba na disku nastavit zero-superblock. Takže zkuste toto:

mdadm -S /dev/md127
mdadm --zero-superblock /dev/sda1

a pak vytvořte nový raid.