Re: /dev/md0 can't be created

[NeilBrown <neilb@suse.de>]

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On Wed, 25 Mar 2015 02:15:34 -0400 (EDT) Xiao Ni <xni@redhat.com> wrote:

> Hi all
> 
>    I have encountered so many times, the raid device is created successfully, but the directory
> /dev/md0 can't be created. It can't reproduce 100%. 
> 
> [root@intel-sugarbay-do-01 create_assemble]# cat /proc/mdstat 
> Personalities : [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
> md0 : active raid10 loop7[7](S) loop6[6] loop5[5] loop4[4] loop3[3] loop2[2] loop1[1] loop0[0]
>       1788416 blocks super 1.2 512K chunks 2 near-copies [7/7] [UUUUUUU]
>       bitmap: 0/1 pages [0KB], 65536KB chunk
> 
> unused devices: <none>
> [root@intel-sugarbay-do-01 create_assemble]# ls /dev/md0
> ls: cannot access /dev/md0: No such file or directory
> 
>     The underline devices are loop devices which are created with big file.
> 
>     The kernel I used is RHEL7 (3.10.0-234.el7.x86_64.debug, mdadm - v3.3.2 - 21st August 2014) 
> I'll try to reproduce this with upstream kernel and mdadm. But I think it shouldn't be the problem about kernel.
> 
>     What do you think I should check for this? And which tool is responsible for creating the directory? Maybe
> I can add some log to it to find the reason.
> 

/dev/md0 is created by udev.
Run
  udevadm monitor

to see the events that udev is processing.  When and ADD event for "md0" is
processed, /dev/md0 should get created.

NeilBrown

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