[linux-lvm] Having duplicate PV problems, think there's a bug in LVM2 md component detection

[Ron Watkins]

I'm sorry if this is a FAQ or if I'm being stupid.  I saw some mentions to 
this problem on the old mailing list, but it didn't seem to quite cover what 
I'm seeing, and I don't see an archive for this list yet.  (and what on 
earth happened to the old list, anyway?)

My problem is this:  I'm setting up a software RAID5 across 5 IDE drives. 
I'm running Debian Unstable, using kernel 2.6.8-2-k7.   I HAVE set 
md_component_detection to 1 in lvm.conf, and I wiped the drives after 
changing this setting.

I originally set it up as a four-drive RAID, via a 3Ware controller, so my 
original devices were sdb, sdc, sdd, and sde. (the machine also has a 
hardware raid on an ICP Vortex SCSI controller: this is sda.)    In this 
mode, it set up and built perfectly.  LVM worked exactly as I expected it 
to.  I had a test volume running.  All the queries and volume management 
worked exactly correctly.  All was well.

So then I tried to add one more drive via the motherboard IDE controller, on 
/dev/hda.  (note that I stopped the array, wiped the first and last 100 megs 
on the drives, and rebuilt. ).  That's when the problems started.  The RAID 
itself seems to build and work just fine, although I haven't waited for the 
entire 6 or so hours it will take to completely finish.  Build speed is 
good, everything seems normal.  But LVM blows up badly in this 
configuration.

When I do a pvcreate on /dev/md0, it succeeds... but if I do a pvdisplay I 
get a bunch of complaints:

jeeves:/etc/lvm# pvdisplay
  Found duplicate PV y8pYTtAg0W703Sc8Wiy79mcWU3gHmCFc: using /dev/sde not 
/dev/hda
  Found duplicate PV y8pYTtAg0W703Sc8Wiy79mcWU3gHmCFc: using /dev/sde not 
/dev/hda
  --- NEW Physical volume ---
  PV Name               /dev/hda
  VG Name
  PV Size               931.54 GB
  Allocatable           NO
  PE Size (KByte)       0
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               y8pYTt-Ag0W-703S-c8Wi-y79m-cWU3-gHmCFc

It seems to think that /dev/hda is where the PV is, rather than /dev/md0.

(Note, again, I *HAVE* turned the md_component_detection to 1 in lvm.conf!!)

I have erased, using dd, the first and last 100 megs or so on every drive, 
and I get exactly the same results every time... even with all RAID and LVM 
blocks erased, if I use this list of drives:

/dev/hda
/dev/sdb
/dev/sdc
/dev/sdd
/dev/sde

with the linux MD driver, LVM does not seem to work properly.  I think the 
component detection is at least a little buggy.  This is what my 
/proc/mdstat looks like:

jeeves:/etc/lvm# cat /proc/mdstat
Personalities : [raid5]
md0 : active raid5 sde[5] sdd[3] sdc[2] sdb[1] hda[0]
      976793600 blocks level 5, 128k chunk, algorithm 2 [5/4] [UUUU_]
      [=>...................]  recovery =  6.2% (15208576/244198400) 
finish=283.7min speed=13448K/sec
unused devices: <none>

I realize that using both IDE and SCSI drives in the same array is 
unusual... but I'm not really using SCSI drives, they just look like that 
because of the 3Ware controller.

Again, this works FINE as long as I just use the (fake) SCSI devices.. it 
doesn't wonk out until I add in /dev/hda.

Any suggestions?  Is this a bug?