How to properly set up RAID1+0 with LVM on 2 physical disks and boot Ubuntu from it?

mercredi 17 août 2016

The scenario is like this: my server contains 2x3TB physical hard drives. I wish to install Ubuntu Server 16.04 on RAID1 (by taking 50GB off the 3TB disks) to keep my server safe in case of a disk failure. I want to use the remaining space (2x 2.95TB) as RAID0 (totaling 5.9TB) for good performance and store large amounts of non-critical data there. After a lot of researching (all this is new to me) I got it working.

The screenshot below shows how I set it all up in the Ubuntu installer.
Ubuntu install partitioner.jpg

To be more precise this is the exact procedure I followed:

Booted the Ubuntu installer in UEFI mode (as my BIOS allowed both UEFI and Legacy for my install medium), GRUB2 menu showed and I started the Ubuntu Installer from there.
Created 2x ESP (EFI System Partition) of 512MiB (sda1 and sdb1).
Created 2x RAID partition of 50GB on sda and sdb.
Created 2x RAID partition of remaining space (2x 2.95TB) on sda and sdb.
Created software RAID1 (md0) of 50GB and RAID0 (md1) of 5.9TB.
Made the raids physical volumes for LVM.
Created a 50GB volume group on md0 called RAID1-vg.
Created a 5.9TB volume group on md1 called RAID0-vg.
Created 2 logical volumes on the RAID1-vg (1 for swap and 1 for Ubuntu root).
Created 1 logical volume on the RAID0-vg (for /home non-critical data).
Created the required filesystems and mountpoints on the logical volumes.
Installed Ubuntu Server 16.04.

Ubuntu installed fine and boots without issues right away. So now my OS installation and swap space are safely stored on RAID1 and my /home directory is mounted on the large 5.9TB RAID0.

Well now, I have a bunch questions about this setup:

First and foremost, is this way of partitioning considered "best practise" for my needs (RAID1 and RAID0 volumes on the same 2 disks)?
Is LVM even the way to go in this setup? Or does it just add a lot of overhead and/or complexity (in particular with rebuilding a degraded RAID and restoring the vg's and lv's in that case)?
GRUB is installed on the EFI partition (ESP) on sda1, how do I install and configure GRUB on sdb1 as well so I can boot when disk sda fails? Will this secondary ESP be kept up-to-date automatically?
How do I configure mdadm so my server will continue to run and boot in case a disk fails?
Once I have everything configured, how do I restore my system (the RAID and LVM setup) in case of a disk failure?

I believe a lot of guides show me part of what I need, but do lots of things a little differently, making that these guides only confuse me more. So that's why I've come here for help. If you have any pointers, suggestions or guides that may help me I would love to hear from you .