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Shamsul Kamal
 asked on

Create new linux software raid without losing data ?

Hi,

I would like to request an assistant.

I have new pair additional drives (With ready Data) and i wish to mirror both of the drive .

May i know whether the following command is safe without losing my data ?

mdadm --create /dev/md4 --metadata=0.90 --level=1 --raid-devices=2 missing /dev/sdd1

For your information i have other running raid device on the server and i would like to add the new /dev/md4 .

Appreciates experts comment whether the above command will works without losing the data inside /dev/sdd1 .

Thank you
LinuxLinux DistributionsLinux OS Dev

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arnold

8/22/2022 - Mon
arnold

You can not use the existing device /dev/sdd1 as the basis for a new one.

You can use an unused space/partition to create a new raid volume.


Your best bet is to use an unallocated/unused space to create a new md device. Then copy the data into it. You can the remove one member and replacing it with another.

Do you use lvm overlay of raid?i.e. you create /dev/mdi and then use pvcreate /dev/mdi then use vgcreate, lvcreate?

If you can provide what disks you have that are currently unused and the space breakdown of the data as well as what is the total size of the of the raid volume you want.
Julian Parker

Before you do anything make sure you have a backup.
Shamsul Kamal

ASKER
Hi,

Actually i already have the following in the current server :

Hard Drive (2 units) (Raid 1)
================

/dev/sda
/dev/sdb

Both of the drive is array for :

/dev/md0
/dev/md1
/dev/md2
/dev/md3

I also have a backup drive :
=====================


/dev/sdc

It is not mounted as a raid array as its only mounted as /backup folder


I wanted to add 2 more drive . 1 unit with data inside, and the other 1 is empty.

So when i plugged in the drive with data it will be detected as /dev/sdd1 and /dev/sde .

I wanted to add into array the new drive with data.

So my question is that whether the data will be wipe off or not after running the following command :

mdadm --create /dev/md4 --metadata=0.90 --level=1 --raid-devices=2 missing /dev/sdd1

I hope this additional info will helps.

Appreciates your assistant.
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arnold

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Shamsul Kamal

ASKER
Hi,

Since i had a backup , i have gone ahead and run the command as follows :

[root@vps1 ~]# mdadm --create /dev/md4 --metadata=0.90 --level=1 --raid-devices=2 missing /dev/sdd1
mdadm: /dev/sdd1 appears to contain an ext2fs file system
    size=976760000K  mtime=Mon Dec 31 00:02:37 2012
Continue creating array? y
mdadm: array /dev/md4 started.
[root@vps1 ~]#


After that i mount the /dev/md4 and all the data is intact.
arnold

great.