What is the correct way to create new raid5 in Linux?

Question

I added some new disks, and tried to create new array, using:

mdadm --create /dev/md/2 --level=5 -x 0 --raid-devices=4/dev/sd{a,b,c,g}2

It creates the array, but after reboot - it's gone. What should I do to keep it visible?

Also - I read about spare disks, and so when I see that the raid was created, and it shows (in /proc/mdstat):

md2 : active (auto-read-only) raid5 sdg2[4](S) sdc2[2] sdb2[1] sda2[0]

I understand that sdg2 is treated as spare. But why isn't it automatically rebuilding/syncing the data?

`What should I do to keep it visible` - fix your mdadm.conf file? — Zoredache, Oct 15 '13 at 20:52

score 3 · Accepted Answer · answered Oct 15 '13 at 20:55

3

You can add all the arrays found on the system to mdadm.conf so it will be started at each boot:

mdadm --examine --scan >> /etc/mdadm/mdadm.conf

Alternatively, you can run mdadm --examine --scan and add the arrays you want manually in mdadm.conf.

answered Oct 15 '13 at 20:55

Kl4m

1

and update-initramfs -u to ensure you get the array correctly loading after reboot! – hookenz Oct 15 '13 at 20:58

score 1 · Answer 2 · answered Oct 16 '13 at 02:49

1

This issue could also arise because of device renaming, Try removing the /dev devices from the ARRAY specification and only use the UUID.

answered Oct 16 '13 at 02:49

Arun Kurian

2 Answers2