[Linux-cluster] CLVMD without GFS

[brem belguebli]

Well,

Pointless, I'm not sure as you take advantage of having all the other nodes
in the cluster updated if a LVM metadata is modified by the node holding the
VG.

Second point, HA-LVM aka hosttags has, IMHO, a security problem as anyone
could modify the hosttag on a VG without any problem (no locking mechanisms
as CLVM).

I have nothing against Clustered FS, but in my specific case, I have to host
serveral Sybase Dataservers on some clusters, and the only acceptable option
for my DBA's is to use raw devices.

I never meant to combine HA-LVM and CLVM, I consider them mutualy exclusive.

Regards

2009/7/21, Christine Caulfield <ccaulfie at redhat.com>:
>
> It seems a little pointless to integrate clvmd with a failover system.
> They're almost totally different ways of running a cluster. clvmd assumes a
> symmetrical cluster (as you've found out) and is designed so that the LVs
> are available on all nodes for a cluster filesystem. Trying to make that
> sort of system work for a failover installation is always going to be
> awkward, it's not what it was designed for.
>
> That, in part I think, is why HA-LVM checks for a clustered VGs and
> declines to manage them. A resource should be controlled by one manager, not
> two, it's just asking for confusion.
>
> Basically you either use clvmd or HA-LVM; not both together.
>
> If you really want to write a resource manager to use clvmd then feel free,
> I don't have any references but others might. It's not an area I have ever
> had to go into.
>
> Good luck ;-)
>
> Chrissie
>
>
>
> On 07/21/2009 03:40 PM, brem belguebli wrote:
>
>> Hi,
>> That's what I 'm trying to do.
>> If you mean lvm.sh, well, I've been playing with it, but it does some
>> "sanity" checks that are wierd
>>
>>   1. It expects HA LVM to be setup (why such check if we want to use
>> CLVM).
>>   2. it exits if it finds a CLVM VG  (kind of funny !)
>>   3. it exits if the lvm.conf is newer than /boot/*.img (about this
>>      one, we tend to prevent the cluster from automatically starting ...)
>>
>> I was looking to find some doc on how to write my own resources, ie CLVM
>> resource that checks if the vg is clustered, if so by which node is it
>> exclusively held, and if the node is down to activate exclusively the VG.
>> If you have some good links to provide me, that'll be great.
>> Thanks
>>
>>
>> 2009/7/21, Christine Caulfield <ccaulfie at redhat.com
>> <mailto:ccaulfie at redhat.com>>:
>>
>>    On 07/21/2009 01:11 PM, brem belguebli wrote:
>>
>>        Hi,
>>        When creating the VG by default clustered, you implicitely
>>        assume that
>>        it will be used with a clustered FS on top of it (gfs, ocfs,
>> etc...)
>>        that will handle the active/active mode.
>>        As I do not intend to use GFS in this particular case, but ext3
>>        and raw
>>        devices, I need to make sure the vg is exclusively activated on one
>>        node, preventing the other nodes to access it unless it is the
>>        failover
>>        procedure (node holding the VG crashed) and then re activate it
>>        exclusively on the failover node.
>>        Thanks
>>
>>
>>
>>    In that case you probably ought to be using rgmanager to do the
>>    failover for you. It has a script for doing exactly this :-)
>>
>>    Chrissie
>>
>>
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