[ceph-users] Using RBD with LVM

John-Paul Robinson jpr at uab.edu
Wed Sep 25 01:39:21 PDT 2013


Thanks.  This fixed the problem.

BTW, after adding this line I still got the same error on my pvcreate
but then I ran pvcreate -vvv and found that it was ignorning my
/dev/rbd1 device because it had detected a partition signature (which I
had added in an earlier attempt to work around this "ignored" issue).

I deleted the partion and the pvcreate worked on all my RBD devices.

A basic recipe for creating an LVM volume is:

for i in 1 2 3
do
  rbd create user1-home-lvm-p0$i --size 102400
  rbd map user1-home-lvm-p0$i
  pvcreate user1-home-lvm-p0$i
done
vgcreate user1-home-vg \
   /dev/rbd/rbd/user1-home-lvm-p01 \
   /dev/rbd/rbd/user1-home-lvm-p02 \
   /dev/rbd/rbd/user1-home-lvm-p03
lvcreate -nuser1-home-lv -l%100FREE user1-home-vg
mkfs.ext4 /dev/user1-home-vg/user1-home-lv
mount /dev/user1-home-vg/user1-home-lv /somewhere

~jpr

On 09/24/2013 07:58 PM, Mandell Degerness wrote:
> You need to add a line to /etc/lvm/lvm.conf:
> 
> types = [ "rbd", 1024 ]
> 
> It should be in the "devices" section of the file.
> 
> On Tue, Sep 24, 2013 at 5:00 PM, John-Paul Robinson <jpr at uab.edu> wrote:
>> Hi,
>>
>> I'm exploring a configuration with multiple Ceph block devices used with
>> LVM.  The goal is to provide a way to grow and shrink my file systems
>> while they are on line.
>>
>> I've created three block devices:
>>
>> $ sudo ./ceph-ls  | grep home
>> jpr-home-lvm-p01: 102400 MB
>> jpr-home-lvm-p02: 102400 MB
>> jpr-home-lvm-p03: 102400 MB
>>
>> And have them mapped into my kernel (3.2.0-23-generic #36-Ubuntu SMP):
>>
>> $ sudo rbd showmapped
>> id pool image            snap device
>> 0  rbd  jpr-test-vol01   -    /dev/rbd0
>> 1  rbd  jpr-home-lvm-p01 -    /dev/rbd1
>> 2  rbd  jpr-home-lvm-p02 -    /dev/rbd2
>> 3  rbd  jpr-home-lvm-p03 -    /dev/rbd3
>>
>> In order to use them with LVM, I need to define them as physical
>> volumes.  But when I run this command I get an unexpected error:
>>
>> $ sudo pvcreate /dev/rbd1
>>   Device /dev/rbd1 not found (or ignored by filtering).
>>
>> I am able to use other RBD on this same machine to create file systems
>> directly and mount them:
>>
>> $ df -h /mnt-test
>> Filesystem      Size  Used Avail Use% Mounted on
>> /dev/rbd0        50G  885M   47G   2% /mnt-test
>>
>> Is there a reason that the /dev/rbd[1-2] devices can't be initialized as
>> physical volumes in LVM?
>>
>> Thanks,
>>
>> ~jpr
>> _______________________________________________
>> ceph-users mailing list
>> ceph-users at lists.ceph.com
>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com


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