From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.2) Gecko/20040809 Description of problem: With udev, creating new raid devices is a bit of a pain, since the device nodes are not there. It would be nice if mdadm would create them when given the -m number flag (or even infer the minor number from the /dev/md%i pattern), if the named devices don't exist. Version-Release number of selected component (if applicable): mdadm-1.5.0-11 How reproducible: Always Steps to Reproduce: 1.mdadm -C /dev/md4 -n 1 -l 2 /dev/hdx1 /dev/hdy1 Actual Results: /dev/md4 does not exist Expected Results: Before udev, we had plenty of raid devices already present in /dev, and this just worked. I wish it would work again. Additional info:
This is solved with mdadm-1.9.0-3. Use the --auto=md flag to create a regular md device file if it doesn't exist or use the --auto=mdp flag to create a partitionable md device if it doesn't exist (but you have to use a name other than /dev/md* when using partitionable devices, for example I created a 16 partition md device on an external FC array using this command: [root@pe-fc4 ~]# mdadm -C /dev/fcarray -l 5 -n 4 --auto=mdp16 /dev/md0 /dev/md1 /dev/md2 /dev/md3 note that I used stacked md devices, and there are some bugs in stacked md device handling in the mdadm-1.9.0 package, specifically it doesn't do mdadm -E properly on stacked devices, but it does start them OK).
I don't think the need for --auto=md is, well, auto enough. If you're using one of the standard device name, I can't think of any reason to not go ahead and create the device if it's not there, since all the info can be inferred from the device name.
I changed the default setting of auto= to do as you wish. As of mdadm-1.11.0-2.fc4 in dist-FC4-HEAD this now works the way you want.