[libvirt-users] best shared storage solution ?

Good day - Is there a way of safely allowing a guest OS to access a disk storage device that is also mounted at the same time by the hypervisor or another guest ? I have Linux LVM volumes containing ext4 and btrfs filestystems that need to be shared between the hypervisor and the guests, and between guests . Attempts to use NFS are too slow to be useable - it takes a guest around 4 hours to uncompress and extract a 10MB tar file (using 4 2.9GHz cores). I need access to the shared file system at all times to use as my /home directory from the hypervisor host, so I guess this rules out iSCSI . I came accross documentation on 'sanlock', but its purpose seems to be antithetical to what I require, as described at: http://libvirt.org/locking.html : " how to ensure a single disk cannot be used by more than one running VM at a time, across any host in a network" - but I want to ensure SAFE concurrent access by multiple VMs or any kernel , either on the hypervisor hardware or in a VM guest, to the same filesystems ( ext4, btrfs ) on the same machine, without having to use a network file system . Can sanlock be used to accomplish this ? Or is there any other method that allows the same filesystem to be safely accessed by more than one kernel running on the same host ? The libvirt documentation is very sketchy on this subject, but I understand that just using the '<shareable/>' in the VM configuration XML is not enough, and a lock manager must be configured - can sanlock be used for this, or is there another lock manager that can ? Thanks & Regards, Jason Vas Dias