raid 0+1 issue

[David Chow]

Dear all,

I find the raidtools-1 (comes with Redhat 7.3) doesn't allow you to run 
raid 0+1. Here is the problem .

I have 2 raid 0 devices /dev/md2 /dev/md3 and then I run raid 1 ontop of 
these raid 0 devices (/dev/md4).

The md2 and md3 sucessfully started, but when come to md4 raidstart 
always return "invalid argument" . The point is that the partition has 
already initialised, but if you run "raidstop /dev/md4" and then it 
cannot start again. If you run "'mkraid /dev/md4" it will initialise the 
raid and start automatically, that means there are some problems that 
the "raidstart" command does not allow raidstart on md devices but the 
mkraid allows you to do that. If anyone have experience please comment 
and advice. Thanks.

regards,
David