You need to download the Red Hat Device Mapper multipath package as it is not provided on the SSIM DVD ISO.
After downloading and transferring the rpm to the SSIM appliance, please make sure to use a md5sum command to check the integrity of the file.
i.e. "md5sum device-mapper-multipath-0.4.9-56.el6.x86_64.rpm" and "md5sum device-mapper-multipath-libs-0.4.9-56.el6.x86_64.rpm"
If you are using SSIM 4.8.1, please use this Article