Re: CentOS 7 install on one RAID 1 [not-so-SOLVED]

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You didn't answer all of the questions I asked, but I'll answer as best I can with the information you gave.

On 01/25/2017 04:47 AM, mark wrote:

Made an md RAID 0 on the raw disks - /dev/sda /dev/sdb. No partitions, nothing.

OK, so right off the bat we have to note that this is not a configuration supported by Red Hat. It is possible to set such a system up, but it may require advanced knowledge of grub2 and mdadm. Because the vendor doesn't support this configuration, and as you've seen, the tools don't always parse out the information they need, you'll forever be responsible for fixing any boot problems that come up. Do you really want that?

I sympathize. I wanted to use full disk RAID, too. I thought that replacing disks would be much easier this way, since there'd just be one md RAID device to manage. That was an attractive option after working with hardware RAID controllers that were easy to manage but expensive, unreliable, and performed very poorly in some conditions. But after a thorough review, I found my earlier suggestion of partitioned RAID with the kickstart and RAID management script I provided was the least work for me, in the long term.

However, when I bring it up, fdisk shows an MBR with no partitions. I can, however, mount /dev/md127p3 as /mnt/sysimage, and all is there.

I assume you're booting with BIOS, then?

One explanation for fdisk showing nothing is that you're using GPT instead of MBR (I think). In order to boot on such a system, you'd need a bios_boot partition at the beginning of the RAID volume to provide enough room for grub2 not to stomp on the first partition with a filesystem.

The other explanation that comes to mind is that you're using an mdadm metadata version stored at the beginning of the drive instead of the end. Do you know what metadata version you used?

Did I need to make a single partition, on each drive, and then make the RAID 1 out of *those*? I don't think I need to have /boot not on a RAID.


That's one option, but it still won't be a supported configuration.

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