Time Machine – Useless for most of us

Time Machine makes incremental backups of your files and puts a fancy user interface on top of it. It works well but it has one big con: it requires an external disk. How useful is that if you are say one of those 1.1 million MacBook (Pro) users (mentioned in the 2007 Q4 financial results) and you need to recover a file you just deleted while you are on the road? Well doh, not at all.

That alone makes Time Machine completely useless for many many MANY people. Interesting fact is that Apple sold about twice as many portable Macs than desktop Macs. I’m not sure who designed Time Machine at Apple, but there sure is a big disconnect here between that solution and what kind of Macs people use.

On the other hand, Time Machine would have been GREAT if Apple had build it on top of Sun’s ZFS filesystem. ZFS can do these snapshots/backups real-time on a life filesystem without requiring an extra disk. You can simply say: ok, here is my Documents folder, and I would like to make a ‘snapshot’ every hour or every time a file changes. That will result in super efficient copies of that folder, containing only the changes. With the ability to go back in time and browse through changes and restore those.

ZFS Snapshots are no replacement for real backups of course. You still want to do that too and ZFS has great support for that. Read what James Gosling (of Java fame) wrote about that on his blog.

Again ZFS magic: when he is on the road he can work on his laptop disk as usual, but then when he is back home the external USB disk is automatically sychronized to contain a hot backup of complete laptop disk. Including the above mentioned snapshots! Awesome.

Unfortunately we are stuck with a half-baked solution that only works for desktop Macs. Missed opportunity Apple. Very Lame.

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3 comments so far

  1. Winni on

    Great. And where do you want Time Machine to backup your files to when you don’t have a second hard disk?

    What you really want is a journaling filesystem, where journaling in this case rather translates to “concurrent versioning file systems”. Unfortunately, there is no commercial desktop operating system available that has this feature built in.

  2. thelameleopard on

    Winni, thank you for your reply. Unfortunately you did not get the piece that I wrote. I will write a better piece in the near future.

    The idea of ZFS is that you get all the Time Machine goodness, the ability to go back in time on your files, WITHOUT needing a second disk. It can do Time Machine functionality on just a single disk!

    A journaling filesystem is not what you want. That is just a feature to improve reliability of the filesystem in case of a crash. Read more about that on http://en.wikipedia.org/wiki/Journaling_file_system for example.

    The feature that we want, and which ZFS provides, is called ‘snapshots’. It is the ability to make ‘remember’ the current state of the disk. So if you make a snapshot of your disk now then you can always refer back to files in that snapshot later on. Even if those files were modified or deleted. It is pretty awesome and a big selling point of ZFS.

    More about snapshots is here: http://en.wikipedia.org/wiki/Snapshot_%28computer_storage%29

    Let’s hope Apple starts using it soon in a future 10.5.x release.

  3. Mario Wolczko on

    Yet more lameness: if you turn FileVault on, TimeMachine is next-to-useless for your home directory.

    When I tried to enable TM I got a message saying that I had to turn FV off and then on again, so turned it off and went to bed while it did its thing.
    Now, when I try to turn it on again I get:

    “You have Time Machine turned on. Time Machine backs up folders protected by FileVault only when you are logged out. You cannot browse or restore individual items of the protected home folder in the Time Machine backup. You can restore all files and folders by using Restore System, available in the Mac OS X Installer.”

    Let’s hope they do a decent job with ZFS.


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