If partitioning a drive with Disk Utility gives you unmount or resource busy errors, there may be workarounds you can use.
When trying to partition and format various USB hard drives, a number of users are getting errors in Disk Utility that states "Disk Erase failed with the error: POSIX reports: The operation couldn't be completed. Cannot allocate memory".
Troubleshooting the Apple Hard Drive updater (#4): Recovering your disk; Terminal can "see" damaged drive; more
Tom and Rafe take a trip down memory lane, describing older, defunct software they used to love... and hate.
You could use this specialized product to make backups against disaster, but it's too much trouble to use as an everyday backup tool.
Migrate Easy is good for one-to-one data transfers between two hard drives in one computer for, say, a small business. However, there are other, more flexible apps available for transferring your data to a brand-new computer.
Pricing not available