raid 0, time machine, Video, la cie

Discussion in 'iMac' started by snowfox, Sep 3, 2010.

  1. snowfox macrumors newbie

    Sep 3, 2010
    I have a new 27'' imac, snow leopard, i7, 8 GB Ram with one 1TB HD

    now I am trying to figure out how to use external lacie drives for
    1.) Time Machine
    2.) Store Video on external drives for editing (maybe in a Raid 0 hardware configuration)
    3.) thinking ... does it make sense to partition a scratch disc for Photoshop CS5 on any of the external drives?

    I did a lot of reading but since I'm just a normal user (mostly photoshop) I don't understand most of the geek talk.

    Here are my assumptions and it would be great if you could correct me in case I'm wrong.

    I can daisy chain multiple external harddrives to my I mac firewire 800 port. I would daisy chain a 1 TB Lacie d2 Quadra for storage of picture files. Another 2 TB lacie would be used exclusively by time machine. For Video and editing in Adobe CS5 Premiere I would daisy chain a lacie 2 big Quadra in a RAID 0 hardware configuration. The internal harddrive I would try to keep rather empty.

    Partitioning - to my understanding - is a bit old school. If I use the internal drive as a scratch disc for Photoshop, OS 10.6 should do a good job to keep the drive defragmented. Photoshop would run fast. No need to partition. If I would use an external drive as a scratch disc I would have to expect photoshop slowing down when it is writing or reading from the scratch disc since firewire 800 isn't as fast as the internal SATA.

    The gains of an external RAID 0 drive opposed to a single HD should be small since FireWire 800 is the bottleneck. In theory fw 800 can transfer 100 MB/s but in real life it is probably is much less. But what would be the real life performance gain of a RAID 0 HD compared to a single HD hooked up to the firewire port? I have no clue - but it would be important to know because this knowledge would effect decisions about Video codecs I should use in my configuration. For example: H.264 does not need a fast harddrive since one layer of video would only need about 4 MB/s however I don't know yet if my CPU can really handle the burden of doing all the coding and decoding. Premiere CS5 can edit H.264 natively (the codec a Canon 5d Mark II uses) but if it really works on my Imac remains to be seen.

    Last assumption: Time machine would back up the data of all drives. The application has no problem with daisy chaining and RAID 0 as long as I keep one drive for this application only and be sure I don't have more data on all other drives together than this drive can backup.
  2. Hellhammer Moderator


    Staff Member

    Dec 10, 2008
    I would use USB drive for backups instead of FireWire. Even if you daisy-chained them, the actual data transfer between the computer and drive(s) is done by a single FW cable that is limited to around 80MB/s in real world. So, if you're using it for video stuff and Time Machine decides to start backing up, you would be bottlenecked. USB drives are also cheaper and the speed ain't that crucial in backups.

    RAID 0 has twice as big risk of failure (if one drive fails, all data is lost) so unless you need more than 3TB which is the biggest capacity available at the moment, I would just stick with unRAIDed setup. As you said, the FW port is the bottleneck as pretty much all 3.5" drives can provide speeds of over 80MB/s.

    I would just use the internal HD as scratch disk for Photoshop, it's faster and 1TB is plenty of space.

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