Unfortunately the wiki is silent on the disk layout and filesystem of the md253. Yet is tells a raidarray is supported, which likely means that always a raid array is used, even using only a single disk. Don't know if this can prevent the datapartition to be mounted by ext2fsd. In linux it does.
But the data partition could also be formatted xfs, and afaik there are no Windows drivers for it.
So I suggest you to boot your PC using a Linux Live CD or -USB stick. Possibly it will automount everything, but on Ubuntu you'll have to install mdadm first. Open a command prompt (terminal) and type (internet access required):
sudo apt-get update
sudo apt-get install mdadm
Probably you'll have an icon on the desktop symbolizing the data partitions. Use the GUI to copy your files.