To Partition, or Not to Partition - RAID.10

Discussion in 'Mac Pro' started by gr8putt, Feb 16, 2018.

  1. gr8putt macrumors newbie

    gr8putt

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    #1
    Hi there -

    Using a MacPro5,1 12-core 3.33, and High Sierra running off a PCIe SSD -

    is it preferable to NOT partition 4x 3.5" 2TB 7200s in a RAID.10, OR,

    would it be reasonable to first partition each of the 4x HDDs identically into 3 vary-sized sections (A/B/C) and then build RAID.10s with each of the 4x A's (small sized), 4x B's (large) and 4x C's (medium)?

    In order to minimize fragmentation, the bulk of the large partition (2nd away from hub) and medium partition (furthest away from hub) are mostly static audio instrument files that are rarely tweaked or modified, but primarily stream data to session work being done on the smaller (closest to the hub) partition which will be the liveliest doing DAW-based audio sessions.

    The alternative, making just one no-partitioned RAID.10 with full capacity of the 4x HDDs, would be to load all the static files first and the most active audio sessions last, hopefully keeping fragmentation to just the outer area of the plates.

    Higher READ speeds are preferred to WRITE speeds.

    Which would you recommend?

    Thank you for your help.
     
  2. lowendlinux Contributor

    lowendlinux

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  3. gr8putt thread starter macrumors newbie

    gr8putt

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    #3
    Thank you for your reply -

    What is IIRC?

    What is Apple SW RAID?

    How does this relevant-to or answer the question posted - to partition, or not to partition for a 5,1 4-Bay High Sierra RAID.10?

    Thank you
     
  4. lowendlinux Contributor

    lowendlinux

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    #4
  5. gr8putt, Feb 16, 2018
    Last edited: Feb 16, 2018

    gr8putt thread starter macrumors newbie

    gr8putt

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    #5
    this is off topic.

    not sure about your intent.

    Thank you for your post.
     
  6. lowendlinux Contributor

    lowendlinux

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    #6
    My intent is to help you with RAID..

    Screen Shot 2018-02-17 at 12.44.33 AM.png
     
  7. jbarley macrumors 68040

    jbarley

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    #7
    Check out this link for more info...
    includes instructions for raid 10
    https://www.lifewire.com/make-raid-with-disk-utility-for-macos-4134293
     
  8. gr8putt, Feb 17, 2018
    Last edited: Feb 17, 2018

    gr8putt thread starter macrumors newbie

    gr8putt

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    #8
    Thanks for the replies.

    RAID.10 = a RAID.0 made from (2x HDDs in RAID.1) + (2x HDDS in RAID.1)

    I've been using Terminal to setup/break RAIDs because the El Capitan Disk Utility couldn't.
    https://www.tekrevue.com/tip/create-raid-el-capitan/

    After skipping Sierra, the MacPro5,1 is now on High Sierra. Putting the SSD boot on a PCIe adapter, I hope to set up the 4 Bays into RAID.10 using 4x 2TB HDDs.

    Does the advantage of partitioning, to avoid heavy iDefrag work over a massive single 4TB RAID.10, outweigh any possible compromise to the seek times for READs and WRITEs, for overall longevity, drive health?

    Any experience/ advice would be very appreciated. Thank you.
     
  9. h9826790 macrumors G5

    h9826790

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    #9
    There is no performance benefit to partiton no matter it’s RAID or not. Unless you intentionally make a partiton to use the outer sectors on the disc, and only use that partiton. Then you will have faster average speed then using the whole drive. However, in this case, the remaining partiton(s) will have lower performance than average. It’s not bad if you know which data you want goes into the fast partiton, and which data should go to the slower partition.

    But in general, making partitons just reduce the flexibility. There is something called “folder” to let you flexiblely origanise the data. One of the big advantage of using folders is when you moving data from one folder to another, the HDD doesn't need to copy anything. Just update the “index”, then the operation is completed. But if you move data from one partiton to another. The HDD will have to physically copy all the data. And even worst, it’s not really 2 separated drives. Therefore, even though you are moving / copying a single large file, there will be still lots of internal mechanical movements between 2 partitons, which will significantly slow down the whole process.

    Also, AFAIK, making partitons actually reduce the OS’s flexibility to use the empty space for defragmentation.

    E.g. partiton 1 is nearly full, partiton 2 is basically empty.

    But due to lack of empty space in partiton 1. The OS now cannot effectively defrag that partiton.

    So, if my understanding is correct. I can’t see how you can get any performance benefit by partitioning a RAID 10 array.
     
  10. gr8putt, Feb 18, 2018
    Last edited: Feb 23, 2018

    gr8putt thread starter macrumors newbie

    gr8putt

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    #10
    Thank you for your reply h9826790, and the several points explained. Appreciated.

    The problem with iDefrag is it does't defragment folders, it first rebuilds the root directory indexes you refer to, then it relocates the entire contents from there. In the past I've used RAID.1 pairs with partitions, for OSX system drive, static data files and active App sessions. The static data files are iDefrag-ed once and they are perfect thereafter.

    This will be a first attempt at setting up 4x 2TB disks as a 4TB RAID.10 (w/ SDD OSX on a PCIe adapter).

    After recent El Capitan updates, I've had a number of drives fail, which is why the interest in RAID10 redundancy and improved 4x Read / 2x Write speeds, and why I'm posting about any possible performance / longevity issues.

    As for my understanding as to the advantage of partitioning, as in the past with RAID.1s, partitioning avoids having to include defragmentation of static data files (1.6TB on a 2TB partition).

    The constant WRITE files of the App Sessions (500.GB partition), DAW recoding software utilizing heavy streaming from the static data Instrument files, are better off partitioned somewhere else because they do need regular defragmentation.

    The 3rd partition is for CCC and Time Machine backups of the SDD OSX (1.5TB partition).

    The current MacPro5,1 3.33 x 12-core (10.13) doesn't need more CPU power or RAM, but it does have issues with G3 speeds. I am hoping things will improve, moving from 2x RAID.1 partitioned pairs to a single RAID.10 partitioned group.

    Again, thank you for your help.
     

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9 February 16, 2018