Assuming you disk setup is as follows:
sda1 and sdb1 as md1 (mirrored) root
sda2 and sdb2 as md0 (striped) boot
sda3, sdb3, sdc1, sdd1 and sde1 as md2 (RAID5) /home
Since you lost drive 2 (sdb) you:
- You lost md0. A stripe needs *all of its drives. You will need to restore this from backup or reinstall it.
- You lost one drive from md1. Since that is a mirror it will still work. (without redundancy atm)
- You lost on drive from md2. Since that is a RAID5 is will work with one drive lost. You should still be able to access all your data.
My first step would be to check my backups. Nothing should go wrong while you fix your RAID arrays. But it is better to be safe and have backups. Since both / and /home are still readable in degraded mode I suggest to start with that.
Afterward pull the broken drive (disk 2, aka sdb), replace it with a new drive and partition the drive. I understood from your comments that it used the same setup as the first drive. Which means that you can configure it correctly from your notes, or 'spy' at sda.
Next fix the three broken RAID arrays.
md0 is lost. You will need to recreate it and restore from backup.
md1 might work with
mdadm --assemble /dev/md1 /dev/sda1 /dev/sdb1
md2 might work with
mdadm --assemble /dev/md2 /dev/sda3 /dev/sdb3 /dev/sdc1 /dev/sdd1 /dev/sde1
Might. I am a BSD guy (not a Linux user) which uses hardware RAID cards. Please double check everything before committing to these commands. This includes your checking your backups.