[CentOS] C7 + UEFI + GPT + RAID1

[Alessandro Baggi]

Update.

I've made another test.
I've create md0 of 8GB and and md1 of 20 gb. After sync completed I've 
rebooted the machine.

When I select partitioning on the installer I get only MDRAID of 500 GB 
and not partitioned size.



> Hi list,
> I'm new with UEFI and GPT.
> For several years I've used MBR partition table. I've installed my
> system on software raid1 (mdadm) using md0(sda1,sdb1) for swap,
> md1(sda2, sdb2) for /, md2 (sda3,sdb3) for /home.  From several how-to
> concerning raid1 installation, I must put each partition on a different
> md devices. I've asked times ago if it's more correct create the md
> device, partitioning it and create fs on each partition created on md
> device:
>
> mdadm create /dev/md0 ...
> fdisk /dev/md0:
> md0p1 swap
> md0p2 /        xfs
> md0p3 /home xfs
>
> or create for each partition an md device and create the fs on mdX
> device directly:
>
> mdadm create /dev/md[012].....
> mkfs.fs /dev/mdX (for each md device)
> md0 swap
> md1 /
> md2 /home
>
> I got as answer that the second solution is the correct solution.
>
> I'm installing C7 1511 on a skylake machine with UEFI and I'm confused.
> After googling, for my installation I must create gpt table, 1 partition
> with fat32 type of 512M, and 2 partition for swap and / (I've excluded
> /home), clone gpt partition table on second disk with sgdisk, create md
> device for swap and /.
>
> I've created gpt partition table with:
>
> 1) part1 512m fat32 EFI-part
> 2) part2 8gb raid  swap
> 3) part3 ~500gb raid /
>
> then I've cloned gpt of sda to sdb without problem.
>
> Then I've created array md0 for swap and md1 for / and then rebooted the
> system.
>
> I've started installation process.
> During disk selection I get only one disk tagged as MDRAID disk and not
> sda and sdb. Selecting MDRAID disk I can't see sda1 sdb1 EFI-part, md0
> and md1 devices.
>
> Going to console, cat /proc/mdstat give me only md1. If I try to start
> md0 mdadm says sda2: not such file or directory but the partition exists
> on /dev/sda.
> Coming back to Installer, it forces me to create partitions on MDRAID
> (md1) disk and I create:
>
> md1p1 EFI
> md1p2 swap
> md1p3 /
>
> Installation was performed an system booted.
>
> Now, on this machine with mbr partition type I get md0 (sda1, sdb1) and
> md1 (sda2, sdb2)
> on uefi machine with gpt I get md1 (sda, sdb).
> I've tried also installing with mbr before using gpt, and I got md0
> (sda1, sdb1), md1(sdb2, sda2) and the other 2 partition for EFI as
> expected. But with mbr installer said me that It gpt was needed.
>
> Why using gpt, if I set two raid partition, create 2 raid, rebooting it
> gives me that md1 has sda and sdb instead sda2 and sdb2 and other md is
> dead?
>
> What is the correct method to install on RAID? 1 md device and create
> partition on it or N md devices for N partition?
>
> Why using gpt I get only one disk on disk selection (mdraid device), not
> the 2 physical disk, and not the 2 md raid created?
>
> Hope in help.
>
> Alessandro.
>
>
>