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

[Stephen Drotar]

Thank you Eric,

Very informative,  If I add 1 Storage Pool on 1TB of data I can only use that Pool for the volumes.  What about Multiple Pools to keep only 2 volumes per pool? Is this achieved by creating what {TYPE} of pool? Not sure about that.

Cheers,

Steve


> On Mar 25, 2015, at 4:43 PM, Eric Blake <eblake at redhat.com> wrote:
> 
> 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
>