host info:
# uname -r && rpm -q qemu-kvm
3.10.0-123.el7.x86_64
qemu-kvm-1.5.3-60.el7.x86_64

VMDK fix is in qemu 2.1, patches for vdi and vpc are on the upstream list.

Since this bz will be fixed in qemu2.1, seems we need to update the component to qemu-kvm-rhev.

Best Regards,
Junyi

Fixed in qemu-kvm-1.5.3-74.el7

verify this issue on qemu-kvm-1.5.3-75.el7.x86_64.
host info:
# uname -r && rpm -q qemu-kvm
3.10.0-123.9.2.el7.x86_64
qemu-kvm-1.5.3-75.el7.x86_64

# qemu-img create -f vmdk gluster://10.66.106.35/volume_sluo/test.vmdk 1G
Formatting 'gluster://10.66.106.35/volume_sluo/test.vmdk', fmt=vmdk size=1073741824 compat6=off zeroed_grain=off 
# qemu-img create -f vpc gluster://10.66.106.35/volume_sluo/test.vpc 1G
Formatting 'gluster://10.66.106.35/volume_sluo/test.vpc', fmt=vpc size=1073741824 
# qemu-img create -f vdi gluster://10.66.106.35/volume_sluo/test.vdi 1G
Formatting 'gluster://10.66.106.35/volume_sluo/test.vdi', fmt=vdi size=1073741824 static=off 
# qemu-img info gluster://10.66.106.35/volume_sluo/test.vmdk
image: gluster://10.66.106.35/volume_sluo/test.vmdk
file format: vmdk
virtual size: 1.0G (1073741824 bytes)
disk size: 16K
Format specific information:
    cid: 1413012394
    parent cid: 4294967295
    create type: monolithicSparse
    extents:
        [0]:
            virtual size: 1073741824
            filename: gluster://10.66.106.35/volume_sluo/test.vmdk
            cluster size: 65536
            format: 
# qemu-img info gluster://10.66.106.35/volume_sluo/test.vpc
image: gluster://10.66.106.35/volume_sluo/test.vpc
file format: vpc
virtual size: 1.0G (1073995776 bytes)
disk size: 12K
cluster_size: 2097152
# qemu-img info gluster://10.66.106.35/volume_sluo/test.vdi
image: gluster://10.66.106.35/volume_sluo/test.vdi
file format: vdi
virtual size: 1.0G (1073741824 bytes)
disk size: 4.5K
cluster_size: 1048576

For qemu-kvm-rhev-2.1.2-1.el7.x86_64 which still fail.
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

Base on above, this issue has been fixed on qemu-kvm-1.5.3-x, I will separate a new bug for qemu-kvm-rhev-2.1.x.

Best Regards,
sluo

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-2015-0349.html