Hard Drives for Video Editing

Discussion in 'Mac Pro' started by MacTO, Jul 6, 2007.

  1. MacTO macrumors member

    MacTO

    Joined:
    Apr 3, 2007
    #1
    Hi all,

    I've got Mac Pro (2 x 2.66 GHz Dual-Core Intel Xeon, 5GB RAM, 250GB SATA 3Gb/s drive) and FCS 2.

    While currently looking at 3 x 400 (or 2 (or 3) x 500)GB hard drives and to RAID them to store the footage (about 9 hours of Beta SP 10 bit... needs about 1TB, I believe) that I'm going to work with, now I'm sort of confused by several questions. :confused: I'll appreciate it if any of these can be answered.

    1. Due to redundancy issue, I'm thinking of RAID 0 and 1 all three (or two) of drives. But, does that mean I need to RAID 1 them to external hard drive(s)?

    2. When you choose hard drives, do you look at seek time for video editing? Since WD Raptor drives are out of the question (too small and too expensive),
    would 8 (or up to 8.9) ms seek time be good enough? Even under RAID?

    3. Does video editing require faster write time? If it does, does it get affected by RAID 1 (write twice... right?) at all?

    4. Or do you consider counting cents per GB when you choose hard drives? Prices may vary from vendor to vendor, but isn't it a smart buy if you choose, for instance, 28 cents/GB (Maxtor) over 35 cents/GB (Seagate) on same 500GB? But does it really matter when the hard drives are RAIDed anyway?

    5. Due to spindle, is it true that 3 x 320GB would run faster than 3 x 500GB under RAID? Or the difference is too small to ignore regardless of seek/write time?

    I apologize in advance if any of those questions doesn't make sense. A newbie to Mac to begin with, I've never done RAID myself, which worries me a bit. Once again, thanks for any insights. :apple:
     
  2. Sean Dempsey macrumors 68000

    Sean Dempsey

    Joined:
    Aug 7, 2006
    #2
    from what I know, you'd want to get a PCI card and an external RAID for the real speed. Mac Pro has software raids only, so if you really want that performance, go for a hardware based, external raid.

    I think.
     
  3. LeviG macrumors 65816

    Joined:
    Nov 6, 2006
    Location:
    Norfolk, UK
    #3
    Agreed, best performance would be a internal to external sata card with raid array in external caddy.
     
  4. crazy-editor macrumors newbie

    Joined:
    Jul 7, 2007
    #4
    Raid 5

    I recommend you RAID 5. You can find on net, what it is. It often uses 4 discs, and the advantage is that if one of them crashes, you can change it to new one and the data are recovered from parity data on the other discs.

    So it is more clever solution than RAID 0 and 1.

    It is fast as 3 disc RAID0.

    And you have to use as external box, like pre-built Lacie, or you can buy discs and box separately. You can use classic SATA discs, at the best discs dedicated to 24/7 usage (sometimes called as "Raid Edition").

    I think that 10bit SD is OK on this.
     
  5. Digital Skunk macrumors 604

    Digital Skunk

    Joined:
    Dec 23, 2006
    Location:
    In my imagination
    #5
    You might find more help over in the special interest forums, then go under video and audio.

    But for the most part you are okay with getting any drive and RAID 0 or 1. But if you want real speed with 10bit video, then getting the external RAID enclosures are the BEST way to go. G-Technology has a whole bunch of them for cheap.... (cheap as in under $3500 with the ability to expand later)

    Your best option for the money is to do what you are doing, but consider the Hitachi 1TB Deskstar for speed and for maximum storage, but you will be paying $800 for two drives. Or get two external eSATA drives and an eSATA PCI card.

    There are so many HDD configuration options that it is quite fun trying to figure out what is best for you. Go to the video forums and read up, you will enjoy it.
     
  6. slughead macrumors 68040

    slughead

    Joined:
    Apr 28, 2004
    #6
    I don't think so. Only on read.

    On write, Raid-5 is slower because it for every [n-1] sectors (where n = the number of hard drives), it has to calculate and write the 'checksum' sector (or whatever it's called).

    For hardcore video editors, raid 0 + 1 (10 ??) is where it's at--top speed, most reliable, least down time if something does go wrong.

    RAID-5 will continue to function if one of the drives dies, unlike RAID 0, but unlike RAID-1, when the drive dies, the performance goes through the floor until you replace and reconfigure it.

    RAID 5 is really neat, but it's not as speedy as RAID 0.

    Quick Rundown of how RAID5 'works'.

    First of all, lemme say that you basically sacrifice 1 hard drive's worth of data out of the array for RAID-5.

    Say you have, I donno, 6 hard drives (you must have 3 or more)

    Think of a file as a big bunch of numbers grouped into sectors.

    Now, divide the sectors in a file into groups of 5.

    Hard drives 1 through 5 will hold sectors 1 through 5. Hard Drive six will hold the sum of sectors 1 through 5. Therefore, if you lose sector 1, you can subtract sectors 2 through 5 (which you still have) from the sum and get sector 1.

    However, every time you write 5 sectors to 5 hard drives, you have to add them up and save the sum to hard drive #6. This is really bothersome and slows the write process down substantially.

    That is highly simplified, what really happens is the hard drive chosen to hold the 'sum' sector changes every time, so each hard drive will hold exactly 1/6 of the sum sectors. This will likely up access time in the event a hard drive dies, when compared to having 1 drive remain constantly responsible for all the summations.

    When a hard drive dies, you'll be informed of it, and you can actually continue to use the remaining drives. The subtraction problem will be done on the fly, so it will be much, much slower, but you can still access the data.

    Later, you may buy a replacement drive and you can use a software program to fix the array good as new (by calculating and copying the missing data).

    The more drives you use in a RAID-5, the less often it will have to do the summations and therefore the speed will increase dramatically.
     
  7. MacTO thread starter macrumors member

    MacTO

    Joined:
    Apr 3, 2007
    #7
    Thanks for everyone's two cents. I really appreciate it.

    I did some more reading about RAID, because I didn't know much of RAID 5, and found that having external drives RAIDed definitely is my best bet like you all pointed out.

    I really liked the idea of RAID 5, but it seems to me that speed still matters when it comes down to video/audio editing, and I also cannot ignore the fact that about 1/5 (or 1/4 is it?) of hard drive space you end up losing.

    Due to the reason I have to invest in PCIe capture card in order to digitize the footage straight from (rental) Beta SP deck into the system (and very low budget in hands), it has left me no other option than just going with something that doesn't allow me to do RAID 5. That's fine. Not everyone drives a Lexus when you only can afford a Honda.

    Once again, thanks so much for your thoughtful inputs.
     
  8. iBeard macrumors regular

    Joined:
    Jan 4, 2005
    #8
    you can partition a RAID 0 section for your scratch disk and then have the rest in a RAID 10 for your data.
     
  9. slughead macrumors 68040

    slughead

    Joined:
    Apr 28, 2004
    #9
    You lose 1 hard drive's worth of information. If you have 5 hard drives, you lose 1/5 the space, if you have 500 hard drives, you lose 1/500 the space.

    RAID 5 requires at least 3 drives. The more, the better.
     

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