Thread: Effects of using both md raid1 and raid0 on same two disks?
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Old 10-Jul-2009, 09:33
ken_yap ken_yap is offline
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Default Re: Effects of using both md raid1 and raid0 on same two dis
There's no problem with RAID-1ing /boot but of course when booting from the BIOS, only one of the disks is accessed. Provided that each component contains a complete filesystem, it will boot. Which is why you can't (software) RAID-5 /boot.

You can even put a bootloader on each disk and if the BIOS will try the secondary if the primary fails to read, it can provide a backup boot. For this you probably have to run grub manually, I'm not sure if the YaST bootloader setup is smart enough. It simple enough:

grub> device (hd0) /dev/sda
grub> root (hd0,0) # or ,1 or wherever /boot is
grub> setup (hd0)

and again for sdb

grub> device (hd0) /dev/sdb
grub> root (hd0,0)
grub> setup (hd0)

Notice that sdb is still addressed as hd0, the first disk. This is the case should the primary disk be unreadable, the secondary becomes the primary disk.

In practice though this fallback feature is very rarely needed so don't fret if you only put the bootloader on sda.
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