[virt-tools-list] Explain the best way to use a 1 TB hd with 6 VMs

[Eric Blake]

On 12/31/1969 05:00 PM,  wrote:
> Hi,
> 
> I’m not understanding the logic behind the storage pool.

It exists mainly to allow remote control of various storage types on a
different host than where you are running your libvirt client.  If you
are doing everything on the same machine, you don't really need to use them.

> 
> 
> Should I 
> 
> A) Partition the boot drive with 6 different partitions and use those with the virt-manager for each VM respectively

Sure, if you want to give each guest the maximum possible bare-metal
performance, at the expense of having fixed-size storage constraints.

But other pools may be smarter, depending on your goals.  An LVM storage
pool gives you performance close to raw-partition, but with the
additional flexibility of letting you resize volumes on the fly.  I
personally find that it is easiest to just use a filesystem pool, and
directly store my images as files (and let my host filesystem worry
about resizing things and mapping to lower-level storage), even though
it adds more overhead for guest accesses, because it is less maintenance
burden to understand what is going on.

> 
> 
> B) Create a storage Pool and if so, do I select physical disk device and create 6 individual volumes

Using the storage pool objects of libvirt (whether by the virt-manager
GUI or by hand) is a way to achieve task A) (that is, a disk-type
storage pool consists of volumes created by making raw partitions within
the disk).  But it is not essential unless you are trying to use
virt-manager on one machine to cause libvirt to create partitions on
another machine.

> 
> C)Which storage TYPE can be used to allocate any capacity for any VM created

Any storage pool that allows growth of volumes (LVM, filesystem, ...),
but not pools where volume creation is fixed-size (disk).

> 
> I’ve tried researching and  now stuck with a LVM Volume Group that seem to serve no purpose, the default Filesystem directory and a Physical Disk Device that allows me to create partitions but keeps the sda1 of 500MB from the boot drive.
> 
> I think creating a physical Disk Device is best but I can only create 1 Storage pool which seem counter-intuitive.

The disk storage pool is tied to the physical disk; you don't create
multiple pools, but multiple volumes within that pool.  That is, it is
perfectly fine for multiple VMs to share a single storage pool, so long
as they are using different volumes within that pool.

> 
> Creating IMGs in the Storage Pool target path caps the amount of storage I can select and allows only 60.0GB at any one time.

It sounds like you are more worried about dynamic sizing, in which case
a disk storage pool is probably not the best option for your setup.
Again, I think that starting from a filesystem pool (just plain old
regular files alongside everything else under /) is the easiest to wrap
your head around while getting used to virtualization, and that the
fancier storage pools are only necessary when you are trying to optimize
your setup.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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