[PVE-User] Storage Questions

[Rakhesh Sasidharan]

Nice! Thanks for the reply Martin. 

Reading about vzdump, I see that another advantage in using LVM would
the ability to have easy backups via snapshots. That's useful.

Thanks,
Rakhesh

On Thu, 25 Nov 2010 18:00 +0000, "Martin Maurer" <martin at proxmox.com>
wrote:
> Hi,
> 
> > -----Original Message-----
> > From: pve-user-bounces at pve.proxmox.com [mailto:pve-user-
> > bounces at pve.proxmox.com] On Behalf Of Rakhesh Sasidharan
> > Sent: Donnerstag, 25. November 2010 17:59
> > To: pve-user at pve.proxmox.com
> > Subject: [PVE-User] Storage Questions
> > 
> > Hi,
> > 
> > (Apologies if these questions are already documented anywhere. I had a
> > quick look at the Proxmox documentation and forums but couldn't find
> > anything.)
> > 
> > I am a new user to Proxmox and KVM in general. Proxmox is excellent, my
> > thanks to all those who created it. :)
> [Martin Maurer] 
> Thanks, you are welcome here.
> > 
> > I have a couple of storage questions.
> > 
> > 1) I note that its possible to add two types of local storage - as LVM or as a
> > directory. Are there any advantages/ disadvantages to each? I have a second
> > hard disk which I'd like to add to my storage pool and my initial thought was
> > to initialize it via LVM, mount in a directory, and then add to Proxmox. But
> > that's when I realized it can take the LVM group directly, so not sure if I
> > should go that route or not.
> 
> [Martin Maurer] 
> Use LVM for the second harddisk and use the block device for virtual
> disks. But this works only for KVM guests. See
> http://pve.proxmox.com/wiki/Storage_Model#LVM_Groups_with_Local_Backing
> You have maximum performance as you are using block devices directly, no
> file system in between.
> 
> > 
> > 2) If I have a second hard disk, are there any performance advantages in
> > moving the virtual machine disk to that machine instead of leaving them on
> > the same disk as Proxmox? I remember reading somewhere (not KVM/
> > Proxmox forums) that if the virtual machines disks are on a separate machine
> > there is less competition between the host OS and the guests for the same
> > disk ...
> [Martin Maurer] 
> Depends a bit on the storage controller but for modern hardware I see no
> difference.  Best is using block device directly (like described above),
> then raw format on the filesystem, qcow2 is the slowest.
> Also think of using a SAN (FC, iSCSI, etc.).
> > 
> > 3) If I have a virtual machine installed in a directory based storage, is there
> > any easy way of moving the OS from that to an LVM storage?
> [Martin Maurer] 
> e.g. with backup/restore. Qmrestore allows to define the destination
> storage.
> Br, martin
> > 
> > Thanks,
> > Rakhesh
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