[CentOS] (C8) root on mdraid

Wed Nov 18 14:56:50 UTC 2020
Łukasz Posadowski <mail at lukaszposadowski.pl>

Mon, 16 Nov 2020 10:29:17 +0000
Tony Mountifield <tony at softins.co.uk>:

> In article
> <20201115123245.db62b8248e1f248afe02844a at lukaszposadowski.pl>, Lukasz
> Posadowski <mail at lukaszposadowski.pl> wrote:
> > 
> > Hello everyone. 
> > 
> > I'm trying to install CentOS 8 with root and swap partitions on
> > software raid. The plan is:
> > - create md0 raid level 1 with 2 hard drives: /dev/sda and /dev/sdb,
> > using Linux Rscue CD,
> > - install CentOS 8 with Virtual Box on my laptop,
> > - rsync CentOS 8 root partition on /dev/md0p1,
> > - chroot in CentOS 8 root partition,
> > - configure /etc/mdadm.conf, grub.cfg, initramfs, install
> > bootloader on both sda and sdb drives.
> > 
> > I think I can do first four of the above, but my CentOS installation
> > acts strange after rebooting the server. It recognizes the raid, but
> > boots randomly with root on /dev/sda1 (and recognizes raid
> > with /dev/sdb disk), or with root on /dev/sdb1 (and recognizes raid
> > with /dev/sda disk). When booting from Linux Rescue CD, the raid
> > with two disk is recognized.
> 
> I thought it was much more usual to partition both disks to give
> sda1,2,3 and sdb1,2,3, and then create /dev/md0 from
> sda1/sdb1, /dev/md1 from sda2/sdb3, and so on.
> 
> That's the way I have always done it, and have never had any problems.
> Never seen an attempt to partition an md device before. In that case,
> how would the kernel and initrd be found in order to assemble the
> RAID?

It totaly works either way - raid on partitions and raid on disks. I'm
use to mirroring whole disks.

-- 
Łukasz Posadowski