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OSX To Feature Portable User Accounts?
eldavojohn writes "A new patent filed by Apple is causing speculation that OSX is soon to receive a new feature. From the article: '[the patent states] that the user account may be stored alongside general data storage or "other functionality". All of which seems to suggest that at some time soon we may be able to load our user accounts onto an iPod, hard drive or USB keydrive and take them wherever we go.'"
Such functionality is already available in Knoppix. Not only can you store your configuration and updates on a USB thumb drive or HD, but the OS itself is portable, too.
Oh, no! You have walked into the slavering fangs of a lurking grue!
The original iPod hard drives (from the 5 and 10 GB models) had a very short guaranteed run time. That wasn't a problem for the iPod as a music player, or for occasional file transfer, since the drive was turned off 90% or more of the time. OS X likes to write to the home directory frequently, though, so "Portable Home Directories" (as they were known at the time) had the potential to wear out the iPod's hard drive very quickly (a matter of weeks or months).
d /mk5002.htm#relia
It turns out that the ACTUAL run time to failure for those drives was typically much longer than promised, so lots of folks have had success with using them as "live" drives. I have no idea what the specs on the current generation of iPod hard drives are, but I'd bet they're considerably more durable.
Hey, what do you know - Toshiba has published the specifications for the original 5GB iPod drive online:
http://www3.toshiba.co.jp/storage/english/spec/hd
That page claims a "product life" of "5 years or 20,000 POH (Power-On-Hours)". 20,000 hours is just over 2.25 years of continuous operation. Given that you can get a 2-year warranty for an iPod through AppleCare these days, that doesn't sound like a very good risk.
I don't happen to have a copy of the original spec sheet we got with the first-generation drives, but my recollection is that the quoted life span was much shorter - short enough that warranty returns for worn-out drives was a real concern if they were kept running all the time, even with the shorter warranties offered at the time (anybody else remember 90-day iPod warranties?).
Of course, for Flash devices (like those in the Shuffle and Nano) the lifetime is specified in terms of a certain number of write operations, rather than total time "turned on". The expected lifetime for an iPod Shuffle used as a home directory is probably very very long - dozens of years.