/sys/block/md0 still present after mdadm -S and -r

/sys/block/md0 still present after mdadm -S and -r

[thomas62186218]

Hi All,

I created an md device as follows:

mdadm -C -f -e 1.0 -R /dev/md0 -l 0 -n 2 -c 32 /dev/sdc1 /dev/sdg1

It was successful and started.

I then want to delete this md device and did as follows:

mdadm -S /dev/md0
mdadm /dev/md0 -r
mdadm --zero-superblock /dev/sdc1
mdadm --zero-superblock /dev/sdg1

I did not receive any errors. Afterwards, md0 was no longer visible in 
/proc/mdstat.

However, there is still /sys/block/md0 entry, as well as an /dev/md0 
entry. I would have expected these to be gone.

Is my md0 not getting fully deleted?

Thanks!
Thomas

Re: /sys/block/md0 still present after mdadm -S and -r

[Neil Brown]

On Friday September 26, thomas62186218@aol.com wrote:
> Hi All,
> 
> I created an md device as follows:
> 
> mdadm -C -f -e 1.0 -R /dev/md0 -l 0 -n 2 -c 32 /dev/sdc1 /dev/sdg1
> 
> It was successful and started.
> 
> I then want to delete this md device and did as follows:
> 
> mdadm -S /dev/md0
> mdadm /dev/md0 -r
> mdadm --zero-superblock /dev/sdc1
> mdadm --zero-superblock /dev/sdg1
> 
> I did not receive any errors. Afterwards, md0 was no longer visible in 
> /proc/mdstat.
> 
> However, there is still /sys/block/md0 entry, as well as an /dev/md0 
> entry. I would have expected these to be gone.
> 
> Is my md0 not getting fully deleted?

The array is completely gone.  That fact that you can still see
/sys/block/md0 is an implementation artifact.  It is very difficult to
make it go away in a race-free way, and there is little cost is
leaving it there.

NeilBrown