[CentOS] virt-manager virtual USB disk unavailable option

Hi, I have installed virt-manager 1.3.2 and I want to create a virtual USB disk (not USB host passthrough) but unfortunately I don't see that option when I try to add a new storage hardware. I have another PC with virt-manager 0.9.5 and Linux Mint and I have that option and it is working

[CentOS] Load Balance between 2 NIC

Hi, I have a server with 2 NIC and 2 different ISP. The idea is configure a Load Balance with these 2 providers. I reviewed: http://lartc.org/lartc.html#LARTC.RPDB.MULTIPLE-LINKS but I would like to know if this is a good method to use with CentOS 6. Thanks in advance!