We help IT Professionals succeed at work.

We've partnered with Certified Experts, Carl Webster and Richard Faulkner, to bring you two Citrix podcasts. Learn about 2020 trends and get answers to your biggest Citrix questions!Listen Now


How to start broken Linux Software RAID ?

Shamsul Kamal
Medium Priority
Last Modified: 2012-05-06

May i know how to start broken linux software raid ?

I have the following :

[root@vps-svr1 ~]# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sdb1[1] sda1[0]
      200704 blocks [2/2] [UU]

md1 : active raid1 sdb3[1] sda3[0]
      2048192 blocks [2/2] [UU]

md3 : active raid1 sdb5[1]
      473845056 blocks [2/1] [_U]

md2 : active raid1 sdb2[1] sda2[2](F)
      12289600 blocks [2/1] [_U]

unused devices: <none>
[root@vps-svr1 ~]#

I have tried the following but no luck ?

[root@vps-svr1 ~]# mdadm --manage /dev/md3 --fail /dev/sdb5
mdadm: set /dev/sdb5 faulty in /dev/md3
[root@vps-svr1 ~]#

[root@vps-svr1 ~]# mdadm --manage /dev/md3 --remove /dev/sdb5
mdadm: hot remove failed for /dev/sdb5: Device or resource busy
[root@vps-svr1 ~]#

[root@vps-svr1 ~]# mdadm --manage --stop /dev/md3
mdadm: fail to stop array /dev/md3: Device or resource busy
[root@vps-svr1 ~]#

[root@vps-svr1 ~]# mdadm --add /dev/md3 /dev/sdb5
mdadm: Cannot open /dev/sdb5: Device or resource busy
[root@vps-svr1 ~]

Appreciates if anybody can provide a step by step on how to update/start the raid.

Thank you.

Watch Question

Hmm I did this not long ago with a RAID 5 array....

If i can remember properly, I just force started the array with the 2 drives and then added the 3rd after...

I think the command your looking for is:

mdadm --manage --run /dev/md3 /dev/sdb5


mdadm --manage /dev/md3 --add /dev/sdXX

give that a shot...

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts
Shamsul KamalJunior Tech



I've tried that but no luck, the following is the result :

[root@vps-svr1 ~]# mdadm --manage --run /dev/md3 /dev/sdb5
mdadm: internal error - devmode[/dev/sdb5]=0
[root@vps-svr1 ~]# mdadm --manage /dev/md3 --add /dev/sdb5
mdadm: Cannot open /dev/sdb5: Device or resource busy
[root@vps-svr1 ~]#

"mdadm: Cannot open /dev/sdb5: Device or resource busy"

Same error I was getting for a bit...

Hmm what do you get when you type:

# mdadm --detail /dev/md3

Shamsul KamalJunior Tech



I managed to rebuild using "mdadm --manage /dev/md3 --add /dev/sda5"

It seems the active raid was sdb5 , i gues that is why the first command did't work.

Ahh... Well, glad to hear its back up.
Shamsul KamalJunior Tech


Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.


Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.