[linux-lvm] Shared LVM questions

[linux-lvm] Shared LVM questions

[Paolo Smiraglia]

Hi to every ones...


I would to setup a LVM build on top of an iSCSI disk shared between
some nodes which is managed by a Master Node (MN) that sents commands
to other nodes (N1, N2,...) through SSH.

I think the cluster extension is not required because a particular
Logical Volume (LV) is accessed exclusively by one node, and because
LVM metadata cannot be modified at the same time by multiple nodes.

One issue is that once a LV is created by a node it cannot be
activated by another node by executing the command

  $> lvchange -aey vg/lv01

and the LV created is a snapshot. The error displayed is

  Can't change logical volume "lv01"


1. In this scenario is CLVMD required?
2. Is it possible to activate a LV in another node?


Thanks in advance for all replies.


-- 
PAOLO SMIRAGLIA
http://portale.isf.polito.it/paolo-smiraglia

Re: [linux-lvm] Shared LVM questions

[Ray Van Dolson]

On Tue, Dec 14, 2010 at 07:59:19AM -0800, Paolo Smiraglia wrote:
> Hi to every ones...
> 
> 
> I would to setup a LVM build on top of an iSCSI disk shared between
> some nodes which is managed by a Master Node (MN) that sents commands
> to other nodes (N1, N2,...) through SSH.
> 
> I think the cluster extension is not required because a particular
> Logical Volume (LV) is accessed exclusively by one node, and because
> LVM metadata cannot be modified at the same time by multiple nodes.
> 
> One issue is that once a LV is created by a node it cannot be
> activated by another node by executing the command
> 
>   $> lvchange -aey vg/lv01
> 
> and the LV created is a snapshot. The error displayed is
> 
>   Can't change logical volume "lv01"
> 
> 
> 1. In this scenario is CLVMD required?
> 2. Is it possible to activate a LV in another node?
> 
> 
> Thanks in advance for all replies.

I haven't tried this, but you probably would need to release the LVM
from use by node B for node A to activate and use it.

Ray

Re: [linux-lvm] Shared LVM questions

[Paolo Smiraglia]

2010/12/14 Ray Van Dolson <rvandolson@esri.com>:
> On Tue, Dec 14, 2010 at 07:59:19AM -0800, Paolo Smiraglia wrote:
>> Hi to every ones...
>>
>>
>> I would to setup a LVM build on top of an iSCSI disk shared between
>> some nodes which is managed by a Master Node (MN) that sents commands
>> to other nodes (N1, N2,...) through SSH.
>>
>> I think the cluster extension is not required because a particular
>> Logical Volume (LV) is accessed exclusively by one node, and because
>> LVM metadata cannot be modified at the same time by multiple nodes.
>>
>> One issue is that once a LV is created by a node it cannot be
>> activated by another node by executing the command
>>
>> � $> lvchange -aey vg/lv01
>>
>> and the LV created is a snapshot. The error displayed is
>>
>> � Can't change logical volume "lv01"
>>
>>
>> 1. In this scenario is CLVMD required?
>> 2. Is it possible to activate a LV in another node?
>>
>>
>> Thanks in advance for all replies.
>
> I haven't tried this, but you probably would need to release the LVM
> from use by node B for node A to activate and use it.
>
> Ray

Hi Ray, thanks for the faster reply...

The problem is that node B is unable to deactivate the Snapshot LV,
because the command

   $> lvchange -aen vg/lv01

fails with the message posted above (Can't change logical volume "lv01").

What is the correct way to deactivate the Snapshot LV in this scenario?

Thanks!


-- 
PAOLO SMIRAGLIA
http://portale.isf.polito.it/paolo-smiraglia