Time Machine - Replacement for Mirrored RAID?

Discussion in 'macOS' started by SilentPanda, Oct 26, 2007.

  1. SilentPanda Moderator emeritus


    Oct 8, 2002
    The Bamboo Forest
    In my Mac Pro I have a 250GB drive and 2x500GB drives. The 250 is used for everything except for my iTunes library which is stored on a mirrored RAID of the 500GB drives. I have an external 250GB drive which I backup my main 250GB drive to every so often.

    Now that Leopard is here does it make sense to continue this? I'm going to do an erase and install. With Time Machine won't the essentially take care of Mirrored RAID except even better? If I use one of the 500GB drives for my main hard drive and the other for Time Machine even if one drive goes bad I should be able to come back to where I was right? I guess the main difference being it's a once a day backup whereas RAID is all the time but that's fine by me.

    Is there something I'm missing here?

    For that matter I think I could even keep most of my files on the 250 including the system disk, put my iTunes stuff on one of the 500's and use the other 500 for the Time Machine drive.

    Yes? No? Try it and let you guys know?
  2. leigh.roy macrumors newbie

    Aug 29, 2007
    mirrored raid is not a backup system.It does nothing to protect you from accidental deletion which is by far the most common cause of data loss.

    Mirrored raid allows you to keep using the system even if one of the disks dies, which Time Machine cannot do.

    They each have a purpose, do not confuse the two of them.
  3. SilentPanda thread starter Moderator emeritus


    Oct 8, 2002
    The Bamboo Forest
    I know Mirrored RAID doesn't help me in the event of file deletion.

    I also know that if my system disk dies I won't be able to keep using my machine. However as long as both my system and time machine disk don't die at the same time, I should be able to restore my old files, hence being almost like mirrored RAID I think. I don't need 24/7 up time and can wait a few days for a new hard drive and even spend time restoring from Time Machine.

    That being said I'm wondering if there is a more ideal set up with the drives I currently have now that Time Machine is available.
  4. FoxyKaye macrumors 68000


    Jan 23, 2004
    Livermore, Terre d'Ange, Bas Lag, Gallifrey
    I've been thinking in a similar vein and when I did a forum search this thread popped up.

    What occurs to me is how much latency your RAID setup introduces on R/W operations. There's always some overhead when using RAID, but it can also be negligible or transparent to the user.

    What makes sense to me based on what you've described is to do the following:

    * Make your two 500GB internal drives the RAID configuration on the system, install Leopard on them and run everything that you've been using from your internal 250 on them (iTunes, movies, etc.). This will create an internal copy in case of drive failure of your entire system.

    * Make the internal 250GB drive your scratch and temporary data HDD. Put nothing on it that you wouldn't mind losing in case of drive failure or other calamity.

    * Replace your external 250GB drive with a 500GB that is the sole domain of Time Machine to back up the mirrored internal 500GB drives.

    * Use your remaining external 250GB drive to either put in a RAID configuration with the internal 250GB drive (this would work better if the internal drive wasn't being used as a scratch disk, since programs doing rendering would need to r/w to both the internal SATA and external drive at the same time, which would definitely introduce some latency), or use the external 250GB drive to make the occasional backup of your temporary data and information on the internal 250GB with a program like DataBackup or even just by dragging and dropping; or, use the remaining external 250GB for your own nefarious purpose.


    I've also been thinking about Time Machine on my iMac, and I think what I'm going to do is pick up an external drive that matches the space of my internal drive for the sole use of Time Machine (should allow it plenty of room for rollbacks and such). I'd originally contemplated using an external drive as a RAID partner for this purposes, but as others have noted, it doesn't do anything about file deletion and an external/internal RAID combination I think would introduce r/w latency.

    This, of course doesn't do anything for my other external drive that has video on it, but maybe I'll make that the purview of Mozy or figure a way to re-organize my capture scratch files so they're picked up by Time Machine.

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