Re: RAID, number of disks supported

[Simon Hobson]

Chris Murphy wrote:
I can consistently boot a /boot on md RAID 0, 1, 4, 5, 6 with 5 disks. At some 
point above that, at least by 8 disks, I get dropped to a grub rescue prompt 
with an error that it can't find 'mduuid/xxxxxxxxxxxxxxxxxxxxxxx'.
Does anyone know off hand what the max number of disk members supported is? Or 
is this a bug? It's either 6 or 7 apparently.

Can't help with that, but if booting into an MD raid environment I make /boot a 
mirrored set (raid 1). By running grub-install to each disk, I get a system 
that can boot from any of the disks - using the partition (eg /dev/sda1) rather 
than the raid set. I've only gone to 5 disks.
However, there's an argument that by the time you reach 3 disks, you gain 
nothing. If you have 3 (or more) disks missing, then failure to be able to boot 
is going to be the least of your worries - raid 6 will only tolerate 2 dead 
disks.

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Simon Hobson

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