[ClusterLabs] Antw: Re: Antw: Re: design of a two-node cluster

Lentes, Bernd bernd.lentes at helmholtz-muenchen.de
Tue Dec 8 09:37:45 EST 2015

Ulrich wrote:
> >
> > Hi Ulrich,
> >
> > the migration i meant is the transition from my current setup (virtual
> > machines in raw files in a partition with filesystem) to the one
> > anticipated in the cluster (virtual machines in blank logical volumes
> > without fs). How can I do that ? And can I expand my disks in the vm
> > afterwards if necessary ?
> If you use LVM, you might just add another disk to the VM, then
> make that disk a PV and add it to the VG. Then you can expand your LVs
> inside the VM.

I like that.

> > But the "other" migration (live-migration of vm's) is of course also
> > interesting. Digimer wrote if I have my vm in a blank logical volume
> > without fs, which is placed on a SAN, I can live-migrate because the
> > process of live-migration takes care about the access to the lv and I
> > don't need a cluster fs, just cLVM.
> If logical volume means LUN (disk), I'd agree. If you mean LVM LV, I'd
> very careful, especially when changing the LVM configuration. If you
> never plan to change LVM configuration, you could consider partitioning
> your disk with GPT with one partition for each VM.

I'm talking about LVM LV. Changing the LVM configuration (resizing a LV,
creating a new LV ...) could happen rarely, but could happen.
But cLVM takes care that during LVM configuration changes the cLVM on the
other notes can't change the configuration, and afterwards propagate the
new configuration to all nodes.
Why be careful ?



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