looking for simple soft raid1 guide

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#1

i have read guide from the following links

  1. http://doc.opensuse.org/products/draft/SLES/SLES-storage_sd_draft/raidroot.html
  2. http://doc.opensuse.org/products/draft/SLES/SLES-storage_sd_draft/raidyast.html

following the instructions i manage to install opensuse13.1 with raid1 with disk1 and disk2.

my question ?

  1. in case of disk1 fail , how do i boot from disk2 .
  2. once I have a replacement for disk1 , how do i do rebuild .after rebuild how do i set it back to boot on disk1
#2
  1. In Raid1, disk1 is a mirror of disk2; if disk1 fails, disk2 takes over automatically; even if this did not happen for some reason, you would still be able to enter recovery mode to sort out the problem because you would not have lost anything (you would just have one copy of it).
  2. It should happen automatically after a rebuild because it knows disk1 is a mirror of disk2.
man mdadm

gives all the options you need to manage raid.

I see you are a newcomer to the forums. Welcome.

#3

On Mon, 04 Aug 2014 20:46:02 +0000, john hudson wrote:

> 1. In Raid1, disk1 is a mirror of disk2; if disk1 fails, disk2 takes
> over automatically; even if this did not happen for some reason, you
> would still be able to enter recovery mode to sort out the problem
> because you would not have lost anything (you would just have one copy
> of it).

Well, since software RAID is implemented in the OS, you might not have
automatic takeover - you might have to make the drive the primary drive,
but as long as it’s mirroring everything on the drive (including the boot
sector), yeah, it should just be a matter of booting from the mirrored
drive.

Jim

–
Jim Henderson
openSUSE Forums Administrator
Forum Use Terms & Conditions at http://tinyurl.com/openSUSE-T-C

#4

On 2014-08-05 00:00, Jim Henderson wrote:
> On Mon, 04 Aug 2014 20:46:02 +0000, john hudson wrote:

> Well, since software RAID is implemented in the OS, you might not have
> automatic takeover - you might have to make the drive the primary drive,
> but as long as it’s mirroring everything on the drive (including the boot
> sector), yeah, it should just be a matter of booting from the mirrored
> drive.

I don’t know how exactly it works, but both disks should have almost
identical MBR and grub code - but not identical, because each one has to
point to different disks.

The BIOS could try to boot disk 1, and if it is missing, it should
automatically try to boot from disk 2.

–
Cheers / Saludos,

Carlos E. R.

(from 13.1 x86_64 “Bottle” (Minas Tirith))

#5

i tried it on virtualbox . i create 2 disks and set it as raid1. no issue in installation and everything running fine after installation .

but when i try remove disk one . it doesn’t boot up on disk2.

I follow the suggestion here and manage to get it boot
https://forums.opensuse.org/showthread.php/393772-How-to-install-bootloader-on-both-disks-with-software-RAID-1

but another problem come up.
i boot using disk1 (remove disk2) and i create a test file1.txt .shutdown then i connect the disk2 and bootup. the file1.txt disappear .
i create a test file2.txt . shutdown and disconnect disk2 and boot up . file1.txt appear while file2.txt disappear .

i know i doing wrong way . i hope someone can post me a proper guide .