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Re: [linux-lvm] Duplicate physical volumes



Dne 25.8.2013 13:28, oliver_block2 web de napsal(a):
Dear LVM list,
this is my first posting to this list and actually I am making my first
experiences with LVM. The following is my situation:
I had a RAID 1 consisting of /dev/sdb1 and /dev/sdc1 making /dev/md2 and used
this device as a physical volume for LVM. I used this inside the volume group
vg_data.
Now I decided to convert this RAID 1 into a RAID 5 by "adding a third and
identical partition /dev/sdd1". It follows how I am going to realize this:
First I removed /dev/sdc1 from /dev/md2 (the old RAID 1) leaving it in
degraded state.
Then I created a new RAID 5, having device name /dev/md0 with a total of three
disks, but running only with two disks for the moment, namely /dev/sdc1 and
/dev/sdd1.
The plan is now to initialize /dev/md0 as a physical volume and add a volume
group and logical volume on top of this. Then I would copy the data from the
old RAID 1 to the new RAID 5. Finally I will remove the old RAID 1 and add the
remaining device /dev/sdb1 to the new RAID 5. Then the conversion would be
complete.
Now the actual problem related to LVM:

You need to make sure you have proper filter rules set in lvm.conf.

While trying to initialize the new /dev/md0 as a pysical volume for LVM, I get
the following message:
# pvcreate /dev/md0
   Incorrect metadata area header checksum on /dev/md0 at offset 3000456183808
   Found duplicate PV LNqPKpqdtqcLkmiqHYOeeVddNYx7FDOq: using /dev/md2 not
/dev/md0
   Can't initialize physical volume "/dev/md0" of volume group "vg_data"
without -ff


When you are destroying previous raids - you should properly wipe disk headers. Otherwise you need to use force options to overwrite existing one, with the risk you could do more damage if you are not 100% what you are doing.

Zdenek


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