The Explorer shows 50MB size for all mapped disks, and I can not find where I can extend their size (until let say 1TB) ? I have administrator rights. I can not copy to these (X, Y etc) disks files more than 50MB, due to the limited disk space.
Yes, you can extend the size of the disks on IX4-300D. To do so, you need to access the LenovoEMC Storage Manager software. From there, you can allocate more space to the disks, allowing for larger file storage.
