On Thu, 30 Dec 2010 16:17:51 -0800 Mark Knecht [off-list ref] wrote:

On Thu, Dec 30, 2010 at 4:16 PM, Mathias Burén [off-list ref] wrote:

quoted

On 31 December 2010 00:14, Mark Knecht [off-list ref] wrote:

quoted

On Thu, Dec 30, 2010 at 4:12 PM, Mathias Burén [off-list ref] wrote:

quoted

On 31 December 2010 00:10, Mark Knecht [off-list ref] wrote:

quoted

Hi,
  What am I forgetting to do? I had a RAID1 using sd{a,b,c}3. I
stopped md3, removed the md3 line in /etc/mdadm.conf, deleted the
partitions using fdisk, and then created 5 new partitions using
sd{a,b,c,d,e}3 to get ready to do a 5 disk RAID6. The new partitions
are the same size as the old ones and located at the same sector
addresses.

  After rebooting, but before creating the new RAID6, I still see md3:

mark@c2stable ~ $ cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md6 : active raid1 sdb6[1] sdc6[2] sda6[0]
     247416933 blocks super 1.1 [3/3] [UUU]

md3 : active raid1 sdc3[2] sdb3[1] sda3[0]
     52436096 blocks [3/3] [UUU]

md5 : active raid1 sdc5[2] sdb5[1] sda5[0]
     52436032 blocks [3/3] [UUU]

unused devices: <none>
mark@c2stable ~ $


  What am I doing wrong or forgetting? I would like md3 to be totally
gone before I create a new md3 in it's place.

Thanks,
Mark
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Erase the superblocks? Recreating partitions doesn't (usually) affect
the data on the HDDs.

// M

Is erasing the superblocks a mdadm operation? I've not heard of that one before.

Thanks,
Mark

Yes, see mdadm --misc. Like:

mdadm --zero-superblock <device>

// M

Yes, just found that.

Can I still use /dev/md3 safely even though it's no longer in
mdadm.conf? I suspect I can?

That sentence doesn't make much sense to me, so I suspect some misunderstand
is going on.  So to be explicit:

  Use
    mdadm --zero-superblock /dev/sdc3 /dev/sdb3 /dev/sda3

 to remove  from those devices any record that they are part of any md array.

Does that clarify thing sufficienty?

NeilBrown

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