[DRBD-user] LVM on drbd confused?

Hari Sekhon hpsekhon at googlemail.com
Fri Feb 13 15:55:35 CET 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Hari Sekhon wrote:
> I am trying to set up a new drbd with lvm on it this time, and after 
> doing
>
> # pvcreate -ff /dev/drbd0
>  Physical volume "/dev/drbd0" successfully created
>
> I get a message which indicates some confusion:
>
> # pvs
>  Found duplicate PV m8M0tNOCx83QS53D07kybsEDl8oNt4X6: using /dev/sdb1 
> not /dev/drbd0
>  Found duplicate PV m8M0tNOCx83QS53D07kybsEDl8oNt4X6: using /dev/drbd0 
> not /dev/sdb1
>  Found duplicate PV m8M0tNOCx83QS53D07kybsEDl8oNt4X6: using /dev/sdb1 
> not /dev/drbd0
>  PV         VG         Fmt  Attr PSize   PFree
>  /dev/sda2  VolGroup00 lvm2 a-   931.19G 880.69G
>  /dev/sdb1             lvm2 --    14.55T  14.55T
>
>
> I don't think it should be touching /dev/sdb1 in case it screws the 
> drbd block device from underneath, there isn't any mention of this 
> behaviour that I can see in the drbd users manual, can anyone point me 
> in the right direction on how to handle this or if it's a problem at all?
>
> Also, this is a 16TB block device created with the very latest 
> drbd-8.3.0 , which was 16TB, so how come doing a pvcreate has left me 
> with 14.55TB, is there really 1.5TB in activity log due to drbd??
>
> Cat /proc/partitions seems to think the drbd device is bigger than 
> that... perhaps I'm misinterpreting but I'd like to know where all 
> that space went.
>
> # cat /proc/partitions
> major minor  #blocks  name
>
>   8    17 15624999983 sdb1
> 147     0 15624523104 drbd0
>
> -h
>
Now when I try to move on regardless, I get an error about device or 
resource busy (a very good thing I think this is some drbd cleverness to 
lock the device from being arbitrarily overwritten underneath the drbd 
layer?)

# lvcreate -L 14TB -n LogVol02 VolGroup01
  Found duplicate PV m8M0tNOCx83QS53D07kybsEDl8oNt4X6: using /dev/sdb1 
not /dev/drbd0
  device-mapper: create ioctl failed: Device or resource busy
  Aborting. Failed to activate new LV to wipe the start of it.

I have tried changing preferred devices to be

preferred_names = [ "^/dev/drbd\d+$" ]

but this doesn't seem to make much difference, even a new pvcreate still 
says

  Found duplicate PV m8M0tNOCx83QS53D07kybsEDl8oNt4X6: using /dev/sdb1 
not /dev/drbd0


Any advice on what I should do about this would be most welcome.

Thanks

-h

-- 
Hari Sekhon
Always open to interesting opportunities
http://www.linkedin.com/in/harisekhon




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