The full installation of OS X Yosemite uses approximately 8.0 GB of disk space for the download and installation, depending on the type of Mac and choices made during the installation.
ISC recommends OS X Yosemite only for Macs that have at least 4.0 GB of RAM.
ISC strongly recommends that all other University users considering an upgrade to OS X Yosemite adopt a 'wait and see' approach, continuing to use earlier supported versions of OS X (i.e., OS X Mavericks, OS X Mountain Lion, and OS X Lion) for at least a week after launch, until the initial bugs and compatibility issues in Yosemite are identified and fixed. ISC will support OS X Yosemite for its clients, including off-campus students, on systems that ship with Yosemite pre-installed. Information Systems & Computing (ISC) and other groups across campus have tested OS X Yosemite and found that it works as expected with many Penn applications and services, including AirPennNet, Box, Exchange, and Zimbra. The golden master release became available on October 16th from the Mac App Store. OS X Yosemite (10.10), formally announced on June 2, 2014, is the ninth significant update to OS X, Apple's desktop operating system.