Answer: No, sorry you need some kind of shared storage device that is accessible by all your pool xen servers.
The easiest way to achieve this is purchase a plain linux box running a serverised version of linux. CentOS 7 and Debian both should work well here.
Hardware should be high quality, because its a Single Point of Failure (SPOF) for your pool. I'd recommend "more smaller disks" rather than "fewer large disks" to increase the throughput.
Then set up an iscsi server and share the disks.
You'll need dedicated gigabit ethernet as a minimum. A channel bond of several gigabit ports would be better, and in a perfect world you'd have a pair of stacked switches to take this traffic redundantly.
The iSCSI network should be isolated from your front-end networks too - a separate VLAN would be the minimum, but dedicated ethernet for iscsi is a good idea.