host info:
# uname -r && rpm -q qemu-kvm-rhev
3.10.0-183.el7.x86_64
qemu-kvm-rhev-2.1.2-1.el7.x86_64

# qemu-img create -f vpc gluster://10.66.106.35/volume_sluo/test2.vpc 1G
Formatting 'gluster://10.66.106.35/volume_sluo/test2.vpc', fmt=vpc size=1073741824 
qemu-img: gluster://10.66.106.35/volume_sluo/test2.vpc: Could not create image: Input/output error

# qemu-img create -f vdi gluster://10.66.106.35/volume_sluo/test3.vdi 1G
Formatting 'gluster://10.66.106.35/volume_sluo/test3.vdi', fmt=vdi size=1073741824 static=off 
qemu-img: gluster://10.66.106.35/volume_sluo/test3.vdi: Could not create image: No such file or directory

Fix included in qemu-kvm-rhev-2.1.2-17.el7

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2015-0624.html