[Ovirt-devel] Modeling LVM storage

Perry N. Myers pmyers at redhat.com
Tue Sep 16 17:08:33 UTC 2008

Steve Ofsthun wrote:
> Chris Lalancette wrote:
>> sseago and I (and variously, other folks) had a somewhat longish 
>> conversation on
>> IRC today about carving up storage with LVM.  This is the second time 
>> we've
>> beaten this horse, so hopefully we are somewhat OK now.  The basic 
>> idea is that,
>> given an iSCSI LUN (and SCSI and FC LUNs in the future), we want to 
>> either:
>> 1)  Assign the entire LUN to a guest (this is the way that ovirt works 
>> right now)
>> 2)  Carve up the LUN using LVM, and then hand out individual logical 
>> volumes to
>> guests.
> How do you plan to distinguish between LVM PVs/LVs created by 
> ovirt/libvirt on iscsi LUNs from LVM PVs/LVs created by guest OSes on 
> directly connected iscsi LUNs?  Just blindly running pvscan will run 
> into all sorts of trouble.

All storage is virtualized.  Guests don't access iSCSI LUNs directly, they 
access it through libvirt storage API.  So this shouldn't be an issue.  If 
we allow guests to directly access iSCSI storage (or other storage) 
directly it bypasses our ability to restrict via oVirt permissions who can 
access what storage and limit storage usage by quotas.


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