[Linux-cluster] Re: Linux-cluster Digest, Preventing LVM from concurrent access

[Rafael Micó Miranda]

Hi Edson,

El lun, 24-08-2009 a las 17:48 -0300, Edson Marquezani Filho escribió:

> 
> When I said validate, I meant just check it out. I didn't expect you
> to run it. Probabily it was not the appropiat word to say what I
> wanted. (I'm sorry for this poor english.)
> 

Ok, don't worry about that. I can't clearly explain myself too.

> > 2.- Filesystem resource: you need to mount the filesystem stored into
> > the logical volume you activate. You need a filesystem to store the VMs,
> > don't you? Or do you use a "raw device" in your Xen service?
> 
> No, I don't and can't do that. LVs are passed directly to VMs'
> configuration files, and Xen takes care of it. Actualy, each LV is
> seen like a phisical disk by the VM. It's Xen that access and "mounts"
> it.
> 

Ok, so you need to use "raw device" for Xen. In this case, your raw
device are the Logical Volumes on top of the Volume Groups. You wont
need any filesystem on them, but anyway you need the LVs. Use the
lvm-cluster resource to take exclusively that LVs and after that use
them as raw devices for Xen. 

> > I updated your pastebin file. I'm not sure if it will be fully
> > funcional.
> >
> > Maybe you should even nest the resources building your service to be
> > sure they are started in order. It will depend on your service. Check my
> > example.
> 
> Hum... so nesting indicates order. It's good to know. =)
> 
> >
> > Yes, but if you have a management console for your VM service you will
> > need a Virtual IP which "floats" with the service, so you can always
> > connect to the same IP to check the status of your virtualization
> > service. You can make that attaching a IP resource to your service.
> >
> 
> What are the changes that needs to be done to lvm.conf, as advised in
> the script code?
> 

You need, at least to set "locking_type = 3" and possibly change your
blacklist of devices. Take a look at the RH documentation:

http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Cluster_Logical_Volume_Manager/lvmconf_file.html



> I have seen that there is already a resource called vm. Maybe,
> lvm-cluster and vm resouces can do everything I need. I hope that it
> can. =)
> 

I don't have any knowledge about that resource script, I'm sorry I can't
help.

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Cheers,

Rafael
-- 
Rafael Micó Miranda