Hi there,
I am trying to set up RAID1 + RAID0 over four disks. I have
md1 = sda2 sdb2 (RAID 1)
md2 = sdc2 sdd2 (RAID 1)
md3 = md1 md2 (RAID 0)
I can successfully mkraid these devices, but when I try to mke2fs I get
the message "Got md request, not good..."
I found the message in the function do_md_request() which simply printk's
the message and returns. This worries me.
I decided to try RAID0 + RAID1 instead, as follows:
md1 = sda2 sdb2 (RAID 0)
md2 = sdc2 sdd2 (RAID 0)
md3 = md1 md2 (RAID 1)
This succeeded without a hitch.
Can somebody explain to me what is going on? Why does RAID 0+1 work where
RAID 1+0 does not?
I would prefer to use 1+0 since this guards against some (but not all) two
disk failures. As an example, say sda and sdc fail. With 1+0 md1 and md2
will both run in degraded mode, and md3 will still be OK. With 0+1 both
md1 and md2 will break, and so md3 will also fail.
Regards,
Corin
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