[PVE-User] Using raw LVM without partitions inside VM

[Brian Hart]

Thanks everyone for the replies.  I've played with the LVM Filters before
but it didn't occur to me to do that in this scenario.  I'll give that a
shot!

Thanks,
Brian




On Sun, Apr 12, 2015 at 11:26 AM, Alexandre DERUMIER <aderumier at odiso.com>
wrote:

> Hi,
>
> I have had a customer with same problem, (raw lvm in guest + lvm disk on
> host for the vms).
>
> The problem is that the host is seeing lvm disks from the guests because
> of vgscan/lvscan.
>
> The solution was to use fileting in lvm.conf of the host, to only scan the
> hosts devices.
>
> I don't remember the config 'filter = [.....]", sorry
>
> ----- Mail original -----
> De: "Brian Hart" <brianhart at ou.edu>
> À: "proxmoxve" <pve-user at pve.proxmox.com>
> Envoyé: Samedi 11 Avril 2015 05:17:57
> Objet: [PVE-User] Using raw LVM without partitions inside VM
>
> Hello everybody,
> For a long time now I've used raw LVM on disks inside of virtual machines
> without using disk partitions. I create a separate small disk to serve for
> the "boot" drive and give it a partition. This is formatted and mounted in
> /boot. Then we create a separate disk to contain everything else in an LVM
> structure. Outside of Proxmox this is perfectly acceptable as long as you
> do not need to boot from the device which we do not since we create that
> separate device. The partition table would only serve as a method for the
> bios to interact with the disk for boot purposes. The main advantage here
> is it makes the non-boot sections of the system very fluid and makes adding
> removing space on a live system SO much easier without having to worry
> about the restrictions of a partition table.
>
> We've been doing this successfully in VMware for a long time but only
> today did we attempt this in Proxmox and ran into a serious issue which
> long story short - resulted in the loss of a disk. I understand what went
> wrong and why this happened and luckily it was just a template that it
> happened to so nothing major lost, we can rebuild it. On Proxmox we use an
> iSCSI SAN with multipath connections for our backend storage so we do LVM
> on proxmox for our disks for our VMs. I know some answers on the forum are
> to "use partitions" and I understand why that is the answer given but we do
> this very intentionally with a deep understanding of how it would normally
> work. The reason it doesn't is because of how the disks are handled on LVM
> backed storage on the host in this case.
>
> What I am hoping for are alternate suggestion on how we can use raw LVM on
> disks with proxmox? Do we need to use a different storage method? Would
> this same problem exist some how with qcow2 files or on a ZFS backed
> storage (such as ZFS over iSCSI)? It seems like it shouldn't for the same
> reasons it doesn't happen on VMware with VMDK files but I wanted to be
> sure. If I understand the issue correctly it should only be because we're
> doing LVM on a raw block device and so the proxmox host sees that directly.
> I would expect something like a qcow2 file would sufficiently shield it but
> maybe not the ZFS over iSCSI(?) I'm not sure. I'm basically looking for any
> creative solutions to accomplish what we are trying to do or any advice
> that doesn't follow the beaten path of "use partitions".
>
> Thanks for any feedback or suggestions --
>
> Brian
>
>
>
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