I decided to make a clean installation of OS X Leopard last night. I had already used Carbon Copy Cloner to copy my Leopard installation DVD to an 8GB partition on one of my USB memory sticks. Having the OS X installation DVD on USB is awesome.
At the tick of 5:44pm, I rebooted my MacBook Pro 1) with the USB memory key attached and 2) while holding the alt/option key down to select a boot drive. I selected the OS X installation partition and opted for the “erase and install” option.
The installation was complete and the system rebooted at 5:53pm. I got through the final setup screens and had the new OS X desktop under my control at 5:54pm. Total time: 10 minutes!
Why was this clean installation so fast? The USB flash memory to SSD flash memory data transfer is much faster than DVD to SSD, and dramatically faster than DVD to spinning HDD.
As a side note, when installing OS X from a flash drive, you don’t have to wait for the standard integrity check of the installation DVD – the verification effort is automatically skipped. I’ve always ditched that step anyway, but for those who allow verification to continue, a good deal of valuable time can be lost. Just another benefit of going all-flash.