[linux-lvm] Configure lvm2 with drbd

[linux-lvm] Configure lvm2 with drbd

[Mariano Gonzalvo]

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Hi,

    I'm trying to configure lvm2 on top of drbd. I've configured drbd 
(/dev/drbd0 and /dev/drbd1) and put them as primary node, but when I try 
to create a physical volume this is what it does happens

       pvcreate /dev/drbd0
          Physical volume "/dev/drbd0" successfully created
       pvdisplay
            --- NEW Physical volume ---
          PV Name               /dev/md4
          VG Name
          PV Size               129,45 GB
          Allocatable           NO
          PE Size (KByte)       0
          Total PE              0
          Free PE               0
          Allocated PE          0
          PV UUID               MtxjHy-8zfW-i9nq-TJA4-b6F9-jtcW-FkanLB

    /dev/md4 is the raid device over was configured drbd0.

    Why /dev/md4 it's taken as PV Name?

Thanks in advance

Best regards

Mariano


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Re: [linux-lvm] Configure lvm2 with drbd

[Patrick Caulfield]

Mariano Gonzalvo wrote:
> Hi,
> 
>     I'm trying to configure lvm2 on top of drbd. I've configured drbd
> (/dev/drbd0 and /dev/drbd1) and put them as primary node, but when I try
> to create a physical volume this is what it does happens
> 
>        pvcreate /dev/drbd0
>           Physical volume "/dev/drbd0" successfully created
>        pvdisplay
>             --- NEW Physical volume ---
>           PV Name               /dev/md4
>           VG Name
>           PV Size               129,45 GB
>           Allocatable           NO
>           PE Size (KByte)       0
>           Total PE              0
>           Free PE               0
>           Allocated PE          0
>           PV UUID               MtxjHy-8zfW-i9nq-TJA4-b6F9-jtcW-FkanLB
> 
>     /dev/md4 is the raid device over was configured drbd0.
> 
>     Why /dev/md4 it's taken as PV Name?
> 

It's trying to be helpful! Normally people build MD devices out of other devices
and so LVM uses the MD in preference to other devices it finds with the same UUID.

You'll need to exclude the MD device in the /etc/lvm/lvm.conf filters entry.
something like:

filter =[ "r/md4/" ]


-- 
Patrick

Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street,
Windsor, Berkshire, SL4 ITE, UK.
Registered in England and Wales under Company Registration No. 3798903

Re: [linux-lvm] Configure lvm2 with drbd

[Bryn M. Reeves]

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Mariano Gonzalvo wrote:
> 
>     /dev/md4 is the raid device over was configured drbd0.
> 
>     Why /dev/md4 it's taken as PV Name?
> 

Hi Mariano,

LVM2 identifies devices using labels written on the disks. So, if md4 is
the underlying device for your drbd devices, when lvm2 scans /dev
looking for labels it finds the label on md4 first and uses that.

You can control this using lvm2's filtering options.

See the man page for lvm.conf for the full details, but editing
/etc/lvm/lvm.conf and changing the filter line from:

        filter = [ "a/.*/" ]

to:

        filter = [ "a|/dev/drdb|", "r|/dev/md|", "a|.*|" ]

Should accept all drdb devices as physical volumes, reject any software
raid (md) devices, and accept everything else.

This should work if you only have PVs on drdb or other device types and
not on any plain md devices. If you have a mix of the types you will
need to create a more specific filter line for your system.

Regards,
Bryn.
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Re: [linux-lvm] Configure lvm2 with drbd

[Mariano Gonzalvo]

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Thanks so much! now it does work ok.

Best regards

Mariano
> Mariano Gonzalvo wrote:
>   
>> Hi,
>>
>>     I'm trying to configure lvm2 on top of drbd. I've configured drbd
>> (/dev/drbd0 and /dev/drbd1) and put them as primary node, but when I try
>> to create a physical volume this is what it does happens
>>
>>        pvcreate /dev/drbd0
>>           Physical volume "/dev/drbd0" successfully created
>>        pvdisplay
>>             --- NEW Physical volume ---
>>           PV Name               /dev/md4
>>           VG Name
>>           PV Size               129,45 GB
>>           Allocatable           NO
>>           PE Size (KByte)       0
>>           Total PE              0
>>           Free PE               0
>>           Allocated PE          0
>>           PV UUID               MtxjHy-8zfW-i9nq-TJA4-b6F9-jtcW-FkanLB
>>
>>     /dev/md4 is the raid device over was configured drbd0.
>>
>>     Why /dev/md4 it's taken as PV Name?
>>
>>     
>
> It's trying to be helpful! Normally people build MD devices out of other devices
> and so LVM uses the MD in preference to other devices it finds with the same UUID.
>
> You'll need to exclude the MD device in the /etc/lvm/lvm.conf filters entry.
> something like:
>
> filter =[ "r/md4/" ]
>
>
>   


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